WO2019022099A1 - Encoding device, decoding device, encoding method and decoding method - Google Patents

Abstract

An encoding device (100) encodes a block, of an image, to be encoded and comprises: a conversion unit (106) that performs a primary conversion by which the residual of the block to be encoded is converted to a primary factor, determines whether to apply a secondary conversion to the block to be encoded, and if a secondary conversion is to be applied, performs a secondary conversion from the primary factor to a secondary factor; a quantization unit (108) that, if a secondary conversion is not applied, calculates a quantized primary factor by performing a first quantization on the primary factor, and if a secondary conversion is applied, calculates a quantized secondary factor by performing a second quantization, which is different from the first quantization, on the secondary factor; and an entropy encoding unit (110) that generates an encoded bitstream by encoding the quantized primary factor or the quantized secondary factor.

Description

Encoding device, decoding device, encoding method and decoding method

The present disclosure relates to an encoding device, a decoding device, an encoding method, and a decoding method.

A video coding standard called HEVC (High-Efficiency Video Coding) is standardized by JCT-VC (Joint Collaborative Team on Video Coding).

H. 265 (ISO / IEC 23008-2 HEVC (High Efficiency Video Coding))

There is a need for further improvements in such encoding and decoding techniques.

Therefore, the present disclosure aims to provide an encoding device, a decoding device, an encoding method, or a decoding method that can realize further improvement.

An encoding apparatus according to an aspect of the present disclosure is an encoding apparatus that encodes a target block to be encoded of an image, and includes a circuit and a memory, and the circuit uses the memory to execute the code. Perform a linear transformation from the residual of the block to be encoded to a primary coefficient, and determine whether or not to apply a quadratic transformation to the block to be encoded, and (i) when the quadratic transformation is not applied, The quantization primary coefficient is calculated by performing the first quantization on the coefficient, and (ii) when the secondary conversion is applied, the secondary conversion from the primary coefficient to the secondary coefficient is performed, and A second coefficient different from the first quantization is applied to the second coefficient to calculate a quantized second coefficient, and encoding is performed by encoding the first coefficient or the second coefficient after quantization. Generate a bitstream

Note that these general or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer readable CD-ROM, a system, a method, an integrated circuit, a computer program And any combination of recording media.

The present disclosure can provide a coding device, a decoding device, a coding method or a decoding method that can realize further improvement.

FIG. 1 is a block diagram showing a functional configuration of the coding apparatus according to the first embodiment. FIG. 2 is a diagram showing an example of block division in the first embodiment. FIG. 3 is a table showing transform basis functions corresponding to each transform type. FIG. 4A is a view showing an example of the shape of a filter used in ALF. FIG. 4B is a view showing another example of the shape of a filter used in ALF. FIG. 4C is a view showing another example of the shape of a filter used in ALF. FIG. 5A is a diagram illustrating 67 intra prediction modes in intra prediction. FIG. 5B is a flowchart for describing an outline of predicted image correction processing by OBMC processing. FIG. 5C is a conceptual diagram for describing an outline of predicted image correction processing by OBMC processing. FIG. 5D is a diagram illustrating an example of FRUC. FIG. 6 is a diagram for describing pattern matching (bilateral matching) between two blocks along a motion trajectory. FIG. 7 is a diagram for describing pattern matching (template matching) between a template in a current picture and a block in a reference picture. FIG. 8 is a diagram for explaining a model assuming uniform linear motion. FIG. 9A is a diagram for describing derivation of a motion vector in units of sub blocks based on motion vectors of a plurality of adjacent blocks. FIG. 9B is a diagram for describing an overview of motion vector derivation processing in the merge mode. FIG. 9C is a conceptual diagram for describing an overview of DMVR processing. FIG. 9D is a diagram for describing an outline of a predicted image generation method using luminance correction processing by LIC processing. FIG. 10 is a block diagram showing a functional configuration of the decoding apparatus according to the first embodiment. FIG. 11 is a flowchart illustrating an example of the conversion process, the quantization process, and the encoding process according to the first embodiment. FIG. 12 is a diagram showing an example of the position of the quantization matrix in the coded bit stream in the first embodiment. FIG. 13 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the first embodiment. FIG. 14 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the second embodiment. FIG. 15 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the second embodiment. FIG. 16 is a flowchart showing an example of derivation processing of the second quantization matrix in the modification of the second embodiment. FIG. 17 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the third embodiment. FIG. 18 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the third embodiment. FIG. 19 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the fourth embodiment. FIG. 20 is a diagram for describing an example of secondary conversion in the fourth embodiment. FIG. 21 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the fourth embodiment. FIG. 22 is a diagram for describing an example of the inverse quadratic conversion in the fourth embodiment. FIG. 23 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the fifth embodiment. FIG. 24 is a flowchart illustrating an example of decoding processing, inverse quantization processing, and inverse transform processing according to the fifth embodiment. FIG. 25 is an overall configuration diagram of a content supply system for realizing content distribution service. FIG. 26 is a diagram illustrating an example of a coding structure at the time of scalable coding. FIG. 27 is a diagram illustrating an example of a coding structure at the time of scalable coding. FIG. 28 is a view showing an example of a display screen of a web page. FIG. 29 is a view showing an example of a display screen of a web page. FIG. 30 is a diagram illustrating an example of a smartphone. FIG. 31 is a block diagram showing a configuration example of a smartphone.

(Findings that formed the basis of this disclosure)
In the next-generation video compression standard, in order to further remove spatial redundancy, a quadratic transform on coefficients obtained by linear transforming a residual is being studied. Even when such secondary transformation is performed, it is expected to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Therefore, an encoding apparatus according to an aspect of the present disclosure is an encoding apparatus that encodes an encoding target block of an image, and includes a circuit and a memory, and the circuit uses the memory. The residual of the encoding target block is subjected to a linear transformation from the residual to the primary coefficient, and it is determined whether or not the secondary transformation is to be applied to the encoding target block, and (i) when the secondary transformation is not applied: A first quantization coefficient is calculated on the first order coefficient to calculate a quantized first order coefficient, and (ii) a second order conversion from the first order coefficient to a second order coefficient is performed when the second order transformation is applied, By performing second quantization different from the first quantization on the second-order coefficient to calculate a quantized second-order coefficient, and encoding the quantized first-order coefficient or the quantized second-order coefficient Generate a coded bit stream.

According to this, different quantization can be performed depending on application / non-application of the secondary transformation to the encoding target block. The second-order coefficient which is quadratically converted from the first-order coefficient represented in the first space is to be expressed in the second-order space other than the first-order space. Therefore, even if the quantization for the first-order coefficient is applied to the second-order coefficient, it is difficult to improve the coding efficiency while suppressing the deterioration of the subjective image quality. For example, the quantization for increasing the loss of the high frequency range component to reduce the loss of the low frequency range component in order to suppress the deterioration of the subjective image quality and to increase the coding efficiency is the first order space and the second order space. It differs in the next space. Therefore, by performing different quantization depending on application / non-application of the secondary transformation to the coding target block, coding is performed while suppressing deterioration in subjective image quality as compared to the case where common quantization is performed. Efficiency can be improved.

Further, in the encoding device according to one aspect of the present disclosure, for example, the first quantization is weighted quantization using a first quantization matrix, and the second quantization is the first quantization matrix. It may be weighted quantization using a different second quantization matrix.

According to this, it is possible to perform weighted quantization using the first quantization matrix as the first quantization. Furthermore, weighted quantization using a second quantization matrix different from the first quantization matrix can be performed as the second quantization. Thus, the first quantization matrix corresponding to the primary space can be used for quantization for the primary coefficients, and the second quantization matrix corresponding to the secondary space can be used for the quantization for the secondary coefficients be able to. Therefore, in both application and non-application of secondary transformation, coding efficiency can be improved while suppressing deterioration in subjective image quality.

Further, in the encoding device according to an aspect of the present disclosure, for example, the circuit may further write the first quantization matrix and the second quantization matrix to the encoded bit stream.

According to this, the first quantization matrix and the second quantization matrix can be included in the coded bit stream. Therefore, it is possible to adaptively determine the first quantization matrix and the second quantization matrix according to the original image, and it is possible to improve the coding efficiency while suppressing the deterioration of the subjective image quality.

Further, in the encoding device according to one aspect of the present disclosure, for example, the primary coefficient includes one or more first primary coefficients and one or more second primary coefficients, and the secondary transformation is Applied to the one or more first linear coefficients and not to the one or more second linear coefficients, the second quantization matrix corresponding to the one or more first linear coefficients Each of the one or more second component values of the second quantization matrix including the above first component value and one or more second component values corresponding to the one or more second primary coefficients; And in accordance with the corresponding component value of the first quantization matrix, in the writing of the second quantization matrix, one or more of the one or more first component values and the one or more second component values. Only the first component value may be written to the coded bit stream.

According to this, each of the one or more second component values of the second quantization matrix can be matched with the corresponding component value of the first quantization matrix. Therefore, it is not necessary to write one or more second component values of the second quantization matrix to the coded bit stream, and coding efficiency can be improved.

In addition, in the encoding device according to an aspect of the present disclosure, for example, in the second transformation, a plurality of predetermined bases are selectively used, and the encoded bit stream is compatible with the plurality of bases. A plurality of second quantization matrices are included, and in the second quantization, the second quantization matrix corresponding to the base used for the secondary transformation is selected from the plurality of second quantization matrices It may be done.

According to this, it is possible to perform the second quantization using the second quantization matrix corresponding to the basis used in the secondary transformation. The features of the quadratic space representing the quadratic coefficients differ depending on the basis used in the quadratic conversion. Therefore, by performing the second quantization using the second quantization matrix corresponding to the base used in the secondary transformation, the second quantization may be performed using the quantization matrix corresponding to the secondary space It is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

In addition, in the encoding device according to an aspect of the present disclosure, for example, the first quantization matrix and the second quantization matrix may be predefined in a standardization standard.

According to this, the first quantization matrix and the second quantization matrix are predefined in the standardization standard. Therefore, the first quantization matrix and the second quantization matrix may not be included in the coded bit stream, and the code amount for the first quantization matrix and the second quantization matrix can be reduced.

Further, in the encoding device according to one aspect of the present disclosure, for example, the circuit may further derive the second quantization matrix from the first quantization matrix.

According to this, the second quantization matrix can be derived from the first quantization matrix. Therefore, since it is not necessary to transmit the second quantization matrix to the decoding device, the coding efficiency can be improved.

Further, in the encoding device according to one aspect of the present disclosure, for example, the primary coefficient includes one or more first primary coefficients and one or more second primary coefficients, and the secondary transformation is Applied to the one or more first linear coefficients and not to the one or more second linear coefficients, the second quantization matrix corresponding to the one or more first linear coefficients Each of the one or more second component values of the second quantization matrix including the above first component value and one or more second component values corresponding to the one or more second primary coefficients; And in accordance with the corresponding component value of the first quantization matrix, in the derivation of the second quantization matrix, the one or more first component values of the second quantization matrix are derived from the first quantization matrix You may

According to this, each of the one or more second component values of the second quantization matrix can be matched with the corresponding component value of the first quantization matrix. Therefore, it is not necessary to derive one or more second component values of the second quantization matrix from the first quantization matrix, and the processing load can be reduced.

Moreover, in the encoding device according to an aspect of the present disclosure, for example, the second quantization matrix may be derived by applying the secondary transformation to the first quantization matrix.

According to this, it is possible to derive the second quantization matrix by applying the secondary transformation to the first quantization matrix. Therefore, the first quantization matrix corresponding to the primary space can be converted to the second quantization matrix corresponding to the secondary space, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

In the encoding device according to one aspect of the present disclosure, for example, the circuit further derives a third quantization matrix from the first quantization matrix, and each component value of the third quantization matrix is The smaller the corresponding component value of the first quantization matrix is, the larger the fourth quantization matrix is derived by applying the secondary transformation to the third quantization matrix, and the fourth quantization matrix is derived from the fourth quantization matrix. A fifth quantization matrix may be derived as the second quantization matrix, and each component value of the fifth quantization matrix may be larger as a corresponding component value of the fourth quantization matrix is smaller.

According to this, it is possible to reduce the influence of the rounding error at the time of secondary conversion on a component having a relatively small value included in the first quantization matrix. That is, it is possible to reduce the influence of the rounding error on the value of the component applied to the coefficient whose loss is desired to be reduced in order to suppress the decrease in subjective image quality. Therefore, the deterioration of the subjective image quality can be further suppressed.

Further, in the encoding device according to one aspect of the present disclosure, for example, each component value of the third quantization matrix is an inverse number of a corresponding component value of the first quantization matrix, and the fifth quantization matrix Each component value of may be the reciprocal of the corresponding component value of the fourth quantization matrix.

According to this, it is possible to use the reciprocal of the corresponding component value of the first quantization matrix / the fourth quantization matrix as each component value of the third quantization matrix / the fifth quantization matrix. Therefore, component values can be derived by simple calculation, and processing load or processing time for deriving the second quantization matrix can be reduced.

Further, in the encoding device according to one aspect of the present disclosure, for example, the first quantization is weighted quantization using a quantization matrix, and the second quantization is a non-weighting that does not use a quantization matrix. It may be attached quantization.

According to this, it is possible to use unweighted quantization without using a quantization matrix as the second quantization. Therefore, while preventing deterioration in subjective image quality by using the first quantization matrix for the first quantization for the second quantization, omission of the code amount or the derivation process of the quantization matrix for the second quantization Can.

Further, in the encoding device according to an aspect of the present disclosure, for example, the first quantization is weighted quantization using a first quantization matrix, and in the secondary transformation, (i) the first-order coefficient A weighted primary coefficient is calculated by multiplying each by the corresponding component value of the weight matrix, (ii) converting the weighted primary coefficient to a secondary coefficient, and in the second quantization, the secondary coefficient Each of the second coefficients may be divided by a common quantization step.

According to this, weighted primary coefficients can be calculated by multiplying each of the primary coefficients by the corresponding component value of the weight matrix. Weighting related to quantization can be performed on the linear coefficients before quadratic conversion. Therefore, when the quadratic transformation is applied, quantization equivalent to weighted quantization can be performed without newly preparing a quantization matrix corresponding to the quadratic space. As a result, it is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Further, in the encoding device according to one aspect of the present disclosure, for example, the circuit may further derive the weight matrix from the first quantization matrix.

According to this, the weight matrix can be derived from the first quantization matrix. Therefore, the code amount for the weight matrix can be reduced, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

Also, in the encoding device according to an aspect of the present disclosure, for example, the circuit may further derive the common quantization step from a quantization parameter for the block to be encoded.

According to this, it is possible to derive the quantization step common to the secondary coefficients of the encoding target block from the quantization parameter. Therefore, it is not necessary to include new information in the coding stream for the common quantization step, and the code amount for the common quantization step can be reduced.

An encoding method according to an aspect of the present disclosure is an encoding method for encoding an encoding target block of an image, which performs linear conversion from residuals of the encoding target block to primary coefficients, and the encoding is performed. It is determined whether or not the second transformation is applied to the target block, and (i) when the second transformation is not applied, the first quantization coefficient is performed on the first coefficient to calculate a quantized first order coefficient (Ii) when applying the second transformation, second transformation of the first-order coefficient to second-order coefficient is performed, and second quantization different from the first quantization is performed on the second-order coefficient To calculate a quantized secondary coefficient, and encode the quantized primary coefficient or the quantized secondary coefficient to generate a coded bit stream.

According to this, it is possible to realize the same effect as the above encoding apparatus.

An encoding apparatus according to an aspect of the present disclosure is an encoding apparatus that encodes a target block to be encoded of an image, and includes a circuit and a memory, and the circuit uses the memory to execute the code. The residual of the encoding target block is subjected to linear conversion to primary coefficients, and it is determined whether or not the secondary conversion is to be applied to the encoding target block, and (i) when the secondary conversion is not applied The first quantization primary coefficient is calculated by performing the first quantization, and (ii) the second quantization is performed by performing the second quantization on the primary coefficient when applying the second transformation Encoding by calculating a first-order coefficient, performing second-order transformation from the second quantization first coefficient to a second-order quantization coefficient, and coding the first-order first quantization coefficient or the second-order quantization coefficient Generate a bitstream

According to this, since the quantization can be performed before the secondary conversion, the secondary conversion can be removed from the loop of the prediction processing when the secondary conversion processing is lossless. Therefore, the load on the processing pipeline can be reduced. In addition, by performing quantization before secondary conversion, it is also possible to simplify the process because it is not necessary to separate the first quantization matrix and the second quantization matrix.

An encoding method according to an aspect of the present disclosure is an encoding method for encoding an encoding target block of an image, wherein the residual of the encoding target block is linearly transformed to primary coefficients, and the encoding target block To determine whether or not to apply a second-order transformation, and (i) calculating the first quantized first-order coefficient by performing the first quantization on the first-order coefficient when the second-order transformation is not applied; (Ii) when the second transformation is applied, second quantization is performed on the first order coefficient to calculate a second quantization first order coefficient, and a second order quantization is calculated from the second quantization first order coefficient A coded bit stream is generated by performing a quadratic conversion to coefficients and encoding the first quantized primary coefficient or the quantized secondary coefficient.

According to this, it is possible to realize the same effect as the above encoding apparatus.

A decoding device according to an aspect of the present disclosure is a decoding device that decodes a block to be decoded of an image, and includes a circuit and a memory, and the circuit uses the memory to generate an encoded bit stream from the encoded bit stream. The quantization coefficient of the block to be decoded is decoded, it is determined whether or not the inverse quadratic transform is applied to the block to be decoded, and when the inverse quadratic transform is not applied, A primary coefficient is calculated by performing inverse quantization, inverse primary transformation from the primary coefficient to the residual of the block to be decoded is performed, and the inverse quadratic transform is applied to the quantization coefficient. The second coefficient is calculated by performing the second inverse quantization different from the first inverse quantization, and the second coefficient is subjected to the inverse quadratic conversion from the second coefficient to the first coefficient, and the first coefficient is used to calculate the decoding target block Perform an inverse linear transformation to the residual .

According to this, it is possible to perform different dequantization depending on application / non-application of the inverse quadratic transform to the block to be decoded. The second-order coefficient which is quadratically converted from the first-order coefficient represented in the first space is to be expressed in the second-order space other than the first-order space. Therefore, even if inverse quantization for the first-order coefficient is applied to the second-order coefficient, it is difficult to improve the coding efficiency while suppressing the deterioration of the subjective image quality. For example, the quantization for increasing the loss of the high frequency range component to reduce the loss of the low frequency range component in order to suppress the deterioration of the subjective image quality and to increase the coding efficiency is the first order space and the second order space. It differs in the next space. Therefore, by performing different inverse quantization depending on application / non-application of inverse quadratic transformation to the block to be decoded, it is possible to suppress deterioration in subjective image quality as compared to the case where common inverse quantization is performed. Coding efficiency can be improved.

In the decoding device according to one aspect of the present disclosure, for example, the first inverse quantization is weighted inverse quantization using a first quantization matrix, and the second inverse quantization is the first quantum. It may be weighted dequantization using a second quantization matrix different from the quantization matrix.

According to this, it is possible to perform weighted inverse quantization using the first quantization matrix as the first inverse quantization. Furthermore, weighted dequantization using a second quantization matrix different from the first quantization matrix can be performed as the second dequantization. Thus, the first quantization matrix corresponding to the primary space can be used for inverse quantization for the primary coefficients, and the second quantization matrix corresponding to the secondary space for inverse quantization for the secondary coefficients Can be used. Therefore, in both application and non-application of the inverse quadratic transform, it is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Further, in the decoding device according to an aspect of the present disclosure, for example, the circuit may further read and interpret the first quantization matrix and the second quantization matrix from the encoded bit stream.

According to this, the first quantization matrix and the second quantization matrix can be included in the coded bit stream. Therefore, it is possible to adaptively determine the first quantization matrix and the second quantization matrix according to the original image, and it is possible to improve the coding efficiency while suppressing the deterioration of the subjective image quality.

Further, in the decoding device according to one aspect of the present disclosure, for example, the second-order coefficient includes one or more first second-order coefficients and one or more second second-order coefficients; A transform is applied to the one or more first quadratic coefficients and is not applied to the one or more second quadratic coefficients, the second quantization matrix The one or more first component values corresponding to the next coefficient, and the one or more second component values corresponding to the one or more second secondary coefficients; Each of the second component values corresponds to the corresponding component value of the first quantization matrix, and in the interpretation of the second quantization matrix, the one or more first component values and the one or more second component values Among the above, only the one or more first component positions may be read and interpreted from the encoded bit stream.

According to this, each of the one or more second component values of the second quantization matrix can be matched with the corresponding component value of the first quantization matrix. Therefore, it is not necessary to decipher one or more second component values of the second quantization matrix from the coded bit stream, and coding efficiency can be improved.

Further, in the decoding device according to an aspect of the present disclosure, for example, in the inverse quadratic transform, a plurality of predetermined bases are selectively used, and the encoded bit stream is compatible with the plurality of bases. A second quantization matrix corresponding to a base used for the inverse quadratic transformation out of the plurality of second quantization matrices in the second inverse quantization. May be selected.

According to this, the features of the quadratic space expressing the quadratic coefficients differ depending on the basis used in the inverse quadratic transformation. Therefore, by performing the second inverse quantization using the second quantization matrix corresponding to the base used in the inverse quadratic conversion, the second inverse quantization is performed using the quantization matrix corresponding to the secondary space. It is possible to improve coding efficiency while suppressing deterioration in subjective image quality.

Also, in the decoding device according to an aspect of the present disclosure, for example, the first quantization matrix and the second quantization matrix may be predefined in a standardization standard.

According to this, the first quantization matrix and the second quantization matrix are predefined in the standardization standard. Therefore, the first quantization matrix and the second quantization matrix may not be included in the coded bit stream, and the code amount for the first quantization matrix and the second quantization matrix can be reduced.

In the decoding device according to an aspect of the present disclosure, for example, the circuit may further derive the second quantization matrix from the first quantization matrix.

According to this, the second quantization matrix can be derived from the first quantization matrix. Therefore, it is not necessary to receive the second quantization matrix from the encoding apparatus, and thus the encoding efficiency can be improved.

Further, in the decoding device according to one aspect of the present disclosure, for example, the second-order coefficient includes one or more first second-order coefficients and one or more second second-order coefficients; A transform is applied to the one or more first quadratic coefficients and is not applied to the one or more second quadratic coefficients, the second quantization matrix The one or more first component values corresponding to the next coefficient, and the one or more second component values corresponding to the one or more second secondary coefficients; Each of the second component values corresponds to the corresponding component value of the first quantization matrix, and the derivation of the second quantization matrix derives the one or more first component positions from the first quantization matrix You may

According to this, each of the one or more second component values of the second quantization matrix can be matched with the corresponding component value of the first quantization matrix. Therefore, it is not necessary to derive one or more second component values of the second quantization matrix from the first quantization matrix, and the processing load can be reduced.

Also, in the decoding device according to an aspect of the present disclosure, for example, the second quantization matrix may be derived by applying a secondary transformation to the first quantization matrix.

According to this, it is possible to derive the second quantization matrix by applying the secondary transformation to the first quantization matrix. Therefore, the first quantization matrix corresponding to the primary space can be converted to the second quantization matrix corresponding to the secondary space, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

Further, in the decoding device according to an aspect of the present disclosure, for example, the circuit further derives a third quantization matrix from the first quantization matrix, and each component value of the third quantization matrix is the The smaller the corresponding component value of the first quantization matrix is, the larger the fourth quantization matrix is derived by applying a secondary transformation to the third quantization matrix, and the fourth quantization matrix is derived from the fourth quantization matrix. The second quantization matrix may be derived, and each component value of the fifth quantization matrix may be larger as a corresponding component value of the fourth quantization matrix is smaller.

According to this, it is possible to reduce the influence of the rounding error at the time of secondary conversion on a component having a relatively small value included in the first quantization matrix. That is, it is possible to reduce the influence of the rounding error on the value of the component applied to the coefficient whose loss is desired to be reduced in order to suppress the deterioration of the subjective image quality. Therefore, the deterioration of the subjective image quality can be further suppressed.

Further, in the decoding device according to one aspect of the present disclosure, for example, each component value of the third quantization matrix is an inverse number of a corresponding component value of the first quantization matrix, and the fifth quantization matrix Each component value may be the reciprocal of the corresponding component value of the fourth quantization matrix.

According to this, it is possible to use the reciprocal of the corresponding component value of the first quantization matrix / the fourth quantization matrix as each component value of the third quantization matrix / the fifth quantization matrix. Therefore, component values can be derived by simple calculation, and processing load or processing time for deriving the second quantization matrix can be reduced.

In the decoding device according to one aspect of the present disclosure, for example, the first inverse quantization is weighted inverse quantization using a quantization matrix, and the second inverse quantization does not use a quantization matrix. It may be unweighted dequantization.

According to this, it is possible to use unweighted dequantization that does not use a quantization matrix as the second dequantization. Therefore, while preventing the deterioration of subjective image quality by using the first quantization matrix for the first inverse quantization for the second inverse quantization, the coding or derivation process of the quantization matrix for the second quantization is omitted. can do.

Further, in the decoding device according to one aspect of the present disclosure, for example, the first inverse quantization is weighted inverse quantization using a first quantization matrix, and in the second inverse quantization, the quantization coefficient is The second-order coefficient is calculated by multiplying each of the above-mentioned quantization coefficients by a common quantization step, and in the inverse quadratic transformation, (i) reverse the second-order coefficient to the weighted first-order coefficient The primary coefficients may be calculated by transforming and (ii) dividing each of the weighted primary coefficients by the corresponding component value of the weight matrix.

According to this, the primary coefficients can be calculated by dividing each of the weighted primary coefficients by the corresponding component value of the weight matrix. In other words, weighting related to quantization can be performed on the primary coefficient before the quadratic conversion. Therefore, when the inverse quadratic transform is applied, inverse quantization equal to weighted inverse quantization can be performed without newly preparing a quantization matrix corresponding to the secondary space. As a result, it is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Further, in the decoding device according to an aspect of the present disclosure, for example, the circuit may further derive the weight matrix from the first quantization matrix.

According to this, the weight matrix can be derived from the first quantization matrix. Therefore, the code amount for the weight matrix can be reduced, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

Further, in the decoding device according to an aspect of the present disclosure, for example, the circuit may further derive the common quantization step from the quantization parameter for the block to be decoded.

According to this, it is possible to derive the quantization step common to the secondary coefficients of the block to be decoded from the quantization parameter. Therefore, it is not necessary to include new information in the coding stream for the common quantization step, and the code amount for the common quantization step can be reduced.

A decoding method according to an aspect of the present disclosure is a decoding method for decoding a block to be decoded of an image, comprising: decoding quantization coefficients of the block to be decoded from a coded bit stream; It is determined whether to apply a transform, and when the inverse quadratic transform is not applied, a primary coefficient is calculated by performing a first inverse quantization on the quantization coefficient, and the decoding is performed from the primary coefficient When performing inverse linear transformation to the residual of the target block and applying the inverse quadratic transformation, the second quantization by performing the second quantization different from the first inverse quantization on the quantization coefficient The next coefficient is calculated, the inverse quadratic transform from the secondary coefficient to the primary coefficient is performed, and the inverse linear transform from the primary coefficient to the residual of the block to be decoded is performed.

According to this, it is possible to realize the same effect as that of the decoding device.

A decoding device according to an aspect of the present disclosure is a decoding device that decodes a block to be decoded of an image, and includes a circuit and a memory, and the circuit uses the memory to generate an encoded bit stream from the encoded bit stream. The quantization coefficient of the block to be decoded is decoded, it is determined whether or not the inverse quadratic transform is applied to the block to be decoded, and when the inverse quadratic transform is not applied, A primary coefficient is calculated by performing inverse quantization, inverse linear transformation is performed from the primary coefficient to the residual of the block to be decoded, and quantization is performed using the quantization coefficient when applying the inverse quadratic transformation. Inverse quadratic transformation to a first order coefficient is performed, and second order quantization is performed on the quantized first order coefficient to calculate a first order coefficient, and the first order coefficient is inverse first transformation to the residual of the block to be decoded I do.

According to this, since the encoding apparatus can perform quantization before the secondary conversion, the secondary conversion can be removed from the loop of the prediction processing if the secondary conversion processing is lossless. Therefore, the load on the processing pipeline can be reduced. In addition, by performing quantization before secondary conversion, it is also possible to simplify the process because it is not necessary to separate the first quantization matrix and the second quantization matrix.

A decoding method according to an aspect of the present disclosure is a decoding method for decoding a block to be decoded of an image, comprising: decoding quantization coefficients of the block to be decoded from a coded bit stream; It is determined whether to apply a transform, and when the inverse quadratic transform is not applied, a primary coefficient is calculated by performing a first inverse quantization on the quantization coefficient, and the decoding is performed from the primary coefficient When the inverse linear transformation to the residual of the target block is performed and the inverse quadratic transformation is applied, the inverse quadratic transformation from the quantization coefficient to the quantized primary coefficient is performed to the quantized primary coefficient A second inverse quantization is performed to calculate a primary coefficient, and an inverse linear transformation is performed from the primary coefficient to the residual of the block to be decoded.

According to this, it is possible to realize the same effect as that of the decoding device.

Note that these general or specific aspects may be realized by a system, an integrated circuit, a computer program, or a recording medium such as a computer readable CD-ROM, and the system, method, integrated circuit, computer program and recording It may be realized by any combination of media.

Embodiments will be specifically described below with reference to the drawings.

The embodiments described below are all inclusive or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the scope of the claims. Further, among the components in the following embodiments, components not described in the independent claim indicating the highest concept are described as arbitrary components.

Embodiment 1
First, an outline of the first embodiment will be described as an example of an encoding apparatus and a decoding apparatus to which the process and / or the configuration described in each aspect of the present disclosure described later can be applied. However, Embodiment 1 is merely an example of an encoding apparatus and a decoding apparatus to which the process and / or the configuration described in each aspect of the present disclosure can be applied, and the processing and / or the process described in each aspect of the present disclosure The configuration can also be implemented in a coding apparatus and a decoding apparatus that are different from the first embodiment.

When the processing and / or configuration described in each aspect of the present disclosure is applied to Embodiment 1, for example, any of the following may be performed.

(1) The encoding apparatus or the decoding apparatus according to the first embodiment corresponds to the constituent elements described in each aspect of the present disclosure among a plurality of constituent elements that configure the encoding apparatus or the decoding apparatus. Replacing a component with a component described in each aspect of the present disclosure (2) A plurality of configurations constituting the encoding device or the decoding device with respect to the encoding device or the decoding device of the first embodiment A component corresponding to the component described in each aspect of the present disclosure, after any change such as addition, replacement, or deletion of a function or processing to be performed on a part of components among elements, is disclosed (3) Addition of processing to the method performed by the encoding apparatus or the decoding apparatus of the first embodiment, and / or a plurality of processes included in the method home Replacing a process corresponding to the process described in each aspect of the present disclosure with the process described in each aspect of the present disclosure after replacing some of the processes and arbitrary changes such as deletion. The component described in each aspect of the present disclosure, the component described in each aspect of the present disclosure is a component of a part of the plurality of components constituting the encoding apparatus or the decoding apparatus of the first aspect Implementing in combination with a component having a part of the functions to be provided or a component performing a part of the process performed by the component described in each aspect of the present disclosure (5) The encoding apparatus according to the first embodiment Or a component having a part of functions provided by a part of a plurality of components constituting the decoding apparatus, or a plurality of components constituting the coding apparatus or the decoding apparatus of the first embodiment Part of A component performing a part of the process performed by the component is a component described in each aspect of the present disclosure, a component provided with a part of the function of the component described in each aspect of the present disclosure, or the present Implementing in combination with a component that performs part of the processing performed by the components described in each aspect of the disclosure (6) For the method performed by the encoding apparatus or the decoding apparatus according to the first embodiment Replacing the processing corresponding to the processing described in each aspect of the present disclosure among the plurality of processing included in the method with the processing described in each aspect of the present disclosure (7) The encoding apparatus according to the first embodiment or Implementing some of the plurality of processes included in the method performed by the decoding device in combination with the processes described in each aspect of the present disclosure

Note that the manner of implementation of the processing and / or configuration described in each aspect of the present disclosure is not limited to the above example. For example, it may be implemented in an apparatus used for a purpose different from the moving picture / image coding apparatus or the moving picture / image decoding apparatus disclosed in the first embodiment, or the process and / or the process described in each aspect. The configuration may be implemented alone. Also, the processes and / or configurations described in the different embodiments may be implemented in combination.

[Overview of Encoding Device]
First, an outline of the coding apparatus according to Embodiment 1 will be described. FIG. 1 is a block diagram showing a functional configuration of coding apparatus 100 according to the first embodiment. The encoding device 100 is a moving image / image coding device that encodes a moving image / image in units of blocks.

As shown in FIG. 1, the encoding apparatus 100 is an apparatus for encoding an image in units of blocks, and includes a dividing unit 102, a subtracting unit 104, a converting unit 106, a quantizing unit 108, and entropy coding. Unit 110, inverse quantization unit 112, inverse transformation unit 114, addition unit 116, block memory 118, loop filter unit 120, frame memory 122, intra prediction unit 124, inter prediction unit 126, And a prediction control unit 128.

The encoding device 100 is realized by, for example, a general-purpose processor and a memory. In this case, when the software program stored in the memory is executed by the processor, the processor controls the division unit 102, the subtraction unit 104, the conversion unit 106, the quantization unit 108, the entropy coding unit 110, and the dequantization unit 112. The inverse transform unit 114, the addition unit 116, the loop filter unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128 function. In addition, coding apparatus 100 includes division section 102, subtraction section 104, conversion section 106, quantization section 108, entropy coding section 110, inverse quantization section 112, inverse conversion section 114, addition section 116, and loop filter section 120. , And may be realized as one or more dedicated electronic circuits corresponding to the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.

Each component included in the encoding device 100 will be described below.

[Division]
The dividing unit 102 divides each picture included in the input moving image into a plurality of blocks, and outputs each block to the subtracting unit 104. For example, the division unit 102 first divides a picture into blocks of a fixed size (for example, 128 × 128). This fixed size block may be referred to as a coding tree unit (CTU). Then, the dividing unit 102 divides each of fixed size blocks into blocks of variable size (for example, 64 × 64 or less) based on recursive quadtree and / or binary tree block division. . This variable sized block may be referred to as a coding unit (CU), a prediction unit (PU) or a transform unit (TU). In the present embodiment, CUs, PUs, and TUs need not be distinguished, and some or all of the blocks in a picture may be processing units of CUs, PUs, and TUs.

FIG. 2 is a diagram showing an example of block division in the first embodiment. In FIG. 2, solid lines represent block boundaries by quadtree block division, and broken lines represent block boundaries by binary tree block division.

Here, the block 10 is a square block (128 × 128 block) of 128 × 128 pixels. The 128x128 block 10 is first divided into four square 64x64 blocks (quadtree block division).

The upper left 64x64 block is further vertically divided into two rectangular 32x64 blocks, and the left 32x64 block is further vertically divided into two rectangular 16x64 blocks (binary block division). As a result, the upper left 64x64 block is divided into two 16x64 blocks 11, 12 and a 32x64 block 13.

The upper right 64x64 block is divided horizontally into two rectangular 64x32 blocks 14 and 15 (binary block division).

The lower left 64x64 block is divided into four square 32x32 blocks (quadtree block division). Of the four 32x32 blocks, the upper left block and the lower right block are further divided. The upper left 32x32 block is vertically divided into two rectangular 16x32 blocks, and the right 16x32 block is further horizontally split into two 16x16 blocks (binary block division). The lower right 32x32 block is divided horizontally into two 32x16 blocks (binary block division). As a result, the lower left 64x64 block is divided into a 16x32 block 16, two 16x16 blocks 17, 18, two 32x32 blocks 19, 20, and two 32x16 blocks 21, 22.

The lower right 64x64 block 23 is not divided.

As described above, in FIG. 2, the block 10 is divided into thirteen variable sized blocks 11 to 23 based on recursive quadtree and binary tree block division. Such division is sometimes called quad-tree plus binary tree (QTBT) division.

Although one block is divided into four or two blocks (quadtree or binary tree block division) in FIG. 2, the division is not limited to this. For example, one block may be divided into three blocks (tri-tree block division). A partition including such a ternary tree block partition may be referred to as a multi type tree (MBT) partition.

[Subtractor]
The subtracting unit 104 subtracts a prediction signal (prediction sample) from an original signal (original sample) in block units divided by the dividing unit 102. That is, the subtraction unit 104 calculates a prediction error (also referred to as a residual) of the encoding target block (hereinafter, referred to as a current block). Then, the subtracting unit 104 outputs the calculated prediction error to the converting unit 106.

The original signal is an input signal of the coding apparatus 100, and is a signal (for example, a luminance (luma) signal and two color difference (chroma) signals) representing an image of each picture constituting a moving image. In the following, a signal representing an image may also be referred to as a sample.

[Converter]
Transform section 106 transforms the prediction error in the spatial domain into a transform coefficient in the frequency domain, and outputs the transform coefficient to quantization section 108. Specifically, the transform unit 106 performs, for example, discrete cosine transform (DCT) or discrete sine transform (DST) determined in advance on the prediction error in the spatial domain.

Transform section 106 adaptively selects a transform type from among a plurality of transform types, and transforms the prediction error into transform coefficients using a transform basis function corresponding to the selected transform type. You may Such transformation may be referred to as explicit multiple core transform (EMT) or adaptive multiple transform (AMT).

The plurality of transformation types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I and DST-VII. FIG. 3 is a table showing transform basis functions corresponding to each transform type. In FIG. 3, N indicates the number of input pixels. The choice of transform type from among these multiple transform types may depend, for example, on the type of prediction (intra-prediction and inter-prediction) or depending on the intra-prediction mode.

Information indicating whether to apply such EMT or AMT (for example, called an AMT flag) and information indicating the selected conversion type are signaled at CU level. Note that the signaling of these pieces of information need not be limited to the CU level, but may be at other levels (eg, sequence level, picture level, slice level, tile level or CTU level).

Also, the conversion unit 106 may re-convert the conversion coefficient (conversion result). Such reconversion may be referred to as adaptive secondary transform (AST) or non-separable secondary transform (NSST). For example, the conversion unit 106 performs reconversion for each sub block (for example, 4 × 4 sub blocks) included in the block of transform coefficients corresponding to the intra prediction error. The information indicating whether to apply the NSST and the information on the transformation matrix used for the NSST are signaled at the CU level. Note that the signaling of these pieces of information need not be limited to the CU level, but may be at other levels (eg, sequence level, picture level, slice level, tile level or CTU level).

Here, Separable conversion is a method in which conversion is performed multiple times by separating in each direction as many as the number of dimensions of the input, and Non-Separable conversion is two or more when the input is multidimensional. This is a method of collectively converting the dimensions of 1 and 2 into one dimension.

For example, as an example of Non-Separable conversion, if the input is a 4 × 4 block, it is regarded as one array having 16 elements, and 16 × 16 conversion is performed on the array There is one that performs transformation processing with a matrix.

Similarly, if you consider 4x4 input blocks as one array with 16 elements, you can perform multiple Givens rotation on the array (Hypercube Givens Transform) as Non-Separable as well. It is an example of conversion.

[Quantizer]
The quantization unit 108 quantizes the transform coefficient output from the transform unit 106. Specifically, the quantization unit 108 scans the transform coefficient of the current block in a predetermined scan order, and quantizes the transform coefficient based on the quantization parameter (QP) corresponding to the scanned transform coefficient. Then, the quantization unit 108 outputs the quantized transform coefficient of the current block (hereinafter, referred to as a quantization coefficient) to the entropy coding unit 110 and the inverse quantization unit 112.

The predetermined order is an order for quantization / inverse quantization of transform coefficients. For example, the predetermined scan order is defined in ascending order (low frequency to high frequency) or descending order (high frequency to low frequency) of the frequency.

The quantization parameter is a parameter that defines a quantization step (quantization width). For example, if the value of the quantization parameter increases, the quantization step also increases. That is, as the value of the quantization parameter increases, the quantization error increases.

[Entropy coding unit]
The entropy coding unit 110 generates a coded signal (coded bit stream) by subjecting the quantization coefficient input from the quantization unit 108 to variable-length coding. Specifically, for example, the entropy coding unit 110 binarizes the quantization coefficient and performs arithmetic coding on the binary signal.

[Inverse quantization unit]
The inverse quantization unit 112 inversely quantizes the quantization coefficient which is the input from the quantization unit 108. Specifically, the inverse quantization unit 112 inversely quantizes the quantization coefficient of the current block in a predetermined scan order. Then, the inverse quantization unit 112 outputs the inverse quantized transform coefficient of the current block to the inverse transform unit 114.

[Inverse converter]
The inverse transform unit 114 restores the prediction error by inversely transforming the transform coefficient which is the input from the inverse quantization unit 112. Specifically, the inverse transform unit 114 restores the prediction error of the current block by performing inverse transform corresponding to the transform by the transform unit 106 on the transform coefficient. Then, the inverse conversion unit 114 outputs the restored prediction error to the addition unit 116.

The restored prediction error does not match the prediction error calculated by the subtracting unit 104 because the information is lost due to quantization. That is, the restored prediction error includes the quantization error.

[Adder]
The addition unit 116 reconstructs the current block by adding the prediction error, which is the input from the inverse conversion unit 114, and the prediction sample, which is the input from the prediction control unit 128. Then, the addition unit 116 outputs the reconstructed block to the block memory 118 and the loop filter unit 120. Reconstruction blocks may also be referred to as local decoding blocks.

[Block memory]
The block memory 118 is a storage unit for storing a block in an encoding target picture (hereinafter referred to as a current picture) which is a block referred to in intra prediction. Specifically, the block memory 118 stores the reconstructed block output from the adding unit 116.

[Loop filter section]
The loop filter unit 120 applies a loop filter to the block reconstructed by the adding unit 116, and outputs the filtered reconstructed block to the frame memory 122. The loop filter is a filter (in-loop filter) used in the coding loop, and includes, for example, a deblocking filter (DF), a sample adaptive offset (SAO), an adaptive loop filter (ALF) and the like.

In ALF, a least squares error filter is applied to remove coding distortion, for example, multiple 2x2 subblocks in the current block, based on local gradient direction and activity. One filter selected from the filters is applied.

Specifically, first, subblocks (for example, 2x2 subblocks) are classified into a plurality of classes (for example, 15 or 25 classes). Sub-block classification is performed based on the gradient direction and activity. For example, the classification value C (for example, C = 5 D + A) is calculated using the gradient direction value D (for example, 0 to 2 or 0 to 4) and the gradient activity value A (for example, 0 to 4). Then, based on the classification value C, the sub-blocks are classified into a plurality of classes (for example, 15 or 25 classes).

The direction value D of the gradient is derived, for example, by comparing gradients in a plurality of directions (for example, horizontal, vertical and two diagonal directions). The gradient activation value A is derived, for example, by adding gradients in a plurality of directions and quantizing the addition result.

Based on the result of such classification, a filter for the subblock is determined among the plurality of filters.

For example, a circularly symmetrical shape is used as the shape of the filter used in ALF. FIGS. 4A to 4C are diagrams showing a plurality of examples of filter shapes used in ALF. FIG. 4A shows a 5 × 5 diamond shaped filter, FIG. 4B shows a 7 × 7 diamond shaped filter, and FIG. 4C shows a 9 × 9 diamond shaped filter. Information indicating the shape of the filter is signaled at the picture level. Note that the signaling of the information indicating the shape of the filter does not have to be limited to the picture level, and may be another level (for example, sequence level, slice level, tile level, CTU level or CU level).

The on / off of the ALF is determined, for example, at the picture level or the CU level. For example, as to luminance, it is determined whether to apply ALF at the CU level, and as to color difference, it is determined whether to apply ALF at the picture level. Information indicating on / off of ALF is signaled at picture level or CU level. Note that the signaling of the information indicating ALF on / off need not be limited to the picture level or CU level, and may be other levels (eg, sequence level, slice level, tile level or CTU level) Good.

The set of coefficients of the plurality of selectable filters (eg, up to 15 or 25 filters) is signaled at the picture level. Note that the signaling of the coefficient set need not be limited to the picture level, but may be other levels (eg, sequence level, slice level, tile level, CTU level, CU level or sub-block level).

[Frame memory]
The frame memory 122 is a storage unit for storing a reference picture used for inter prediction, and may be referred to as a frame buffer. Specifically, the frame memory 122 stores the reconstructed block filtered by the loop filter unit 120.

[Intra prediction unit]
The intra prediction unit 124 generates a prediction signal (intra prediction signal) by performing intra prediction (also referred to as in-screen prediction) of the current block with reference to a block in the current picture stored in the block memory 118. Specifically, the intra prediction unit 124 generates an intra prediction signal by performing intra prediction with reference to samples (for example, luminance value, color difference value) of a block adjacent to the current block, and performs prediction control on the intra prediction signal. Output to the part 128.

For example, the intra prediction unit 124 performs intra prediction using one of a plurality of predefined intra prediction modes. The plurality of intra prediction modes include one or more non-directional prediction modes and a plurality of directional prediction modes.

One or more non-directional prediction modes are described, for example, in It includes Planar prediction mode and DC prediction mode defined in H.265 / High-Efficiency Video Coding (HEVC) standard (Non-Patent Document 1).

The plurality of directionality prediction modes are, for example, H. It includes 33 directional prediction modes defined by the H.265 / HEVC standard. In addition to the 33 directions, the plurality of directionality prediction modes may further include 32 direction prediction modes (a total of 65 directionality prediction modes). FIG. 5A is a diagram showing 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. Solid arrows indicate H. A broken line arrow represents the added 32 directions, which represents the 33 directions defined in the H.265 / HEVC standard.

Note that a luminance block may be referred to in intra prediction of a chrominance block. That is, the chrominance component of the current block may be predicted based on the luminance component of the current block. Such intra prediction may be referred to as cross-component linear model (CCLM) prediction. The intra prediction mode (for example, referred to as a CCLM mode) of a chrominance block referencing such a luminance block may be added as one of the intra prediction modes of the chrominance block.

The intra prediction unit 124 may correct the pixel value after intra prediction based on the gradient of the reference pixel in the horizontal / vertical directions. Intra prediction with such correction is sometimes called position dependent intra prediction combination (PDPC). Information indicating the presence or absence of application of PDPC (for example, called a PDPC flag) is signaled, for example, at CU level. Note that the signaling of this information need not be limited to the CU level, but may be at other levels (eg, sequence level, picture level, slice level, tile level or CTU level).

[Inter prediction unit]
The inter prediction unit 126 performs inter prediction (also referred to as inter-frame prediction) of a current block with reference to a reference picture that is a reference picture stored in the frame memory 122 and that is different from the current picture. Generate a prediction signal). Inter prediction is performed in units of a current block or sub blocks (for example, 4 × 4 blocks) in the current block. For example, the inter prediction unit 126 performs motion estimation on the current block or sub block in the reference picture. Then, the inter prediction unit 126 generates an inter prediction signal of the current block or sub block by performing motion compensation using motion information (for example, a motion vector) obtained by the motion search. Then, the inter prediction unit 126 outputs the generated inter prediction signal to the prediction control unit 128.

The motion information used for motion compensation is signaled. A motion vector predictor may be used to signal the motion vector. That is, the difference between the motion vector and the predicted motion vector may be signaled.

Note that the inter prediction signal may be generated using not only the motion information of the current block obtained by the motion search but also the motion information of the adjacent block. Specifically, the inter prediction signal is generated in units of sub blocks in the current block by weighting and adding a prediction signal based on motion information obtained by motion search and a prediction signal based on motion information of an adjacent block. It may be done. Such inter prediction (motion compensation) may be called OBMC (overlapped block motion compensation).

In such an OBMC mode, information indicating the size of the sub-block for the OBMC (for example, called the OBMC block size) is signaled at the sequence level. Also, information indicating whether or not to apply the OBMC mode (for example, called an OBMC flag) is signaled at the CU level. Note that the level of signaling of these pieces of information need not be limited to the sequence level and the CU level, and may be other levels (eg, picture level, slice level, tile level, CTU level or subblock level) Good.

The OBMC mode will be described more specifically. FIG. 5B and FIG. 5C are a flowchart and a conceptual diagram for explaining an outline of predicted image correction processing by OBMC processing.

First, a predicted image (Pred) by normal motion compensation is acquired using the motion vector (MV) assigned to the encoding target block.

Next, the motion vector (MV_L) of the encoded left adjacent block is applied to the current block to obtain a predicted image (Pred_L), and the predicted image and Pred_L are weighted and superimposed. Perform the first correction of the image.

Similarly, the motion vector (MV_U) of the encoded upper adjacent block is applied to the coding target block to obtain a predicted image (Pred_U), and the predicted image subjected to the first correction and the Pred_U are weighted. A second correction of the predicted image is performed by adding and superposing, and this is made a final predicted image.

Although the two-step correction method using the left adjacent block and the upper adjacent block has been described here, the right adjacent block and the lower adjacent block may be used to perform correction more than two steps. It is possible.

The area to be superimposed may not be the pixel area of the entire block, but only a partial area near the block boundary.

Although the predicted image correction processing from one reference picture has been described here, the same applies to the case where a predicted image is corrected from a plurality of reference pictures, and after obtaining a corrected predicted image from each reference picture The final predicted image is obtained by further superimposing the obtained predicted images.

The processing target block may be a prediction block unit or a sub block unit obtained by further dividing the prediction block.

As a method of determining whether to apply the OBMC process, for example, there is a method using obmc_flag which is a signal indicating whether to apply the OBMC process. As a specific example, in the encoding apparatus, it is determined whether the encoding target block belongs to a complex area of motion, and if it belongs to a complex area of motion, the value 1 is set as obmc_flag. The encoding is performed by applying the OBMC processing, and when not belonging to the complex region of motion, the value 0 is set as the obmc_flag and the encoding is performed without applying the OBMC processing. On the other hand, the decoding apparatus decodes the obmc_flag described in the stream, and switches whether to apply the OBMC process according to the value to perform decoding.

The motion information may be derived on the decoding device side without being signalized. For example, H. The merge mode defined in the H.265 / HEVC standard may be used. Also, for example, motion information may be derived by performing motion search on the decoding device side. In this case, motion search is performed without using the pixel value of the current block.

Here, a mode in which motion estimation is performed on the decoding device side will be described. The mode in which motion estimation is performed on the side of the decoding apparatus may be referred to as a pattern matched motion vector derivation (PMMVD) mode or a frame rate up-conversion (FRUC) mode.

An example of the FRUC process is shown in FIG. 5D. First, referring to motion vectors of encoded blocks spatially or temporally adjacent to the current block, a plurality of candidate lists (which may be common to the merge list) each having a predicted motion vector are generated Be done. Next, the best candidate MV is selected from among the plurality of candidate MVs registered in the candidate list. For example, an evaluation value of each candidate included in the candidate list is calculated, and one candidate is selected based on the evaluation value.

Then, a motion vector for the current block is derived based on the selected candidate motion vector. Specifically, for example, the selected candidate motion vector (best candidate MV) is derived as it is as the motion vector for the current block. Also, for example, a motion vector for the current block may be derived by performing pattern matching in a peripheral region of a position in the reference picture corresponding to the selected candidate motion vector. That is, the search is performed on the area around the best candidate MV by the same method, and if there is an MV for which the evaluation value is good, the best candidate MV is updated to the MV and the current block is updated. It may be used as the final MV. In addition, it is also possible to set it as the structure which does not implement the said process.

When processing is performed in units of subblocks, the same processing may be performed.

The evaluation value is calculated by calculating the difference value of the reconstructed image by pattern matching between the area in the reference picture corresponding to the motion vector and the predetermined area. Note that the evaluation value may be calculated using information other than the difference value.

As pattern matching, first pattern matching or second pattern matching is used. The first pattern matching and the second pattern matching may be referred to as bilateral matching and template matching, respectively.

In the first pattern matching, pattern matching is performed between two blocks in two different reference pictures, which are along the motion trajectory of the current block. Therefore, in the first pattern matching, a region in another reference picture along the motion trajectory of the current block is used as the predetermined region for calculation of the evaluation value of the candidate described above.

FIG. 6 is a diagram for explaining an example of pattern matching (bilateral matching) between two blocks along a motion trajectory. As shown in FIG. 6, in the first pattern matching, among pairs of two blocks in two reference pictures (Ref0, Ref1) which are two blocks along the motion trajectory of the current block (Cur block), Two motion vectors (MV0, MV1) are derived by searching for the most matching pair. Specifically, for the current block, a reconstructed image at a designated position in the first encoded reference picture (Ref 0) designated by the candidate MV, and a symmetric MV obtained by scaling the candidate MV at a display time interval. The difference with the reconstructed image at the specified position in the second coded reference picture (Ref 1) specified in step is derived, and the evaluation value is calculated using the obtained difference value. The candidate MV with the best evaluation value among the plurality of candidate MVs may be selected as the final MV.

Under the assumption of continuous motion trajectory, motion vectors (MV0, MV1) pointing to two reference blocks are the temporal distance between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1) It is proportional to (TD0, TD1). For example, when the current picture is temporally located between two reference pictures, and the temporal distances from the current picture to the two reference pictures are equal, in the first pattern matching, the mirror symmetric bi-directional motion vector Is derived.

In the second pattern matching, pattern matching is performed between a template in the current picture (a block adjacent to the current block in the current picture (eg, upper and / or left adjacent blocks)) and a block in the reference picture. Therefore, in the second pattern matching, a block adjacent to the current block in the current picture is used as the predetermined area for calculating the evaluation value of the candidate described above.

FIG. 7 is a diagram for explaining an example of pattern matching (template matching) between a template in a current picture and a block in a reference picture. As shown in FIG. 7, in the second pattern matching, the current block (Cur Pic) is searched for in the reference picture (Ref 0) for a block that most closely matches a block adjacent to the current block (Cur block). Motion vectors are derived. Specifically, for the current block, the reconstructed image of the left adjacent region and / or the upper adjacent encoded region and the encoded reference picture (Ref 0) specified by the candidate MV are equivalent to each other. When the difference between the position and the reconstructed image is derived, the evaluation value is calculated using the obtained difference value, and the candidate MV having the best evaluation value among the plurality of candidate MVs is selected as the best candidate MV Good.

Information indicating whether to apply such a FRUC mode (for example, called a FRUC flag) is signaled at the CU level. In addition, when the FRUC mode is applied (for example, when the FRUC flag is true), a signal (for example, called a FRUC mode flag) indicating a method of pattern matching (for example, first pattern matching or second pattern matching) is a signal at CU level Be Note that the signaling of these pieces of information need not be limited to the CU level, but may be at other levels (eg, sequence level, picture level, slice level, tile level, CTU level or subblock level) .

Here, a mode for deriving a motion vector based on a model assuming uniform linear motion will be described. This mode is sometimes referred to as a bi-directional optical flow (BIO) mode.

FIG. 8 is a diagram for explaining a model assuming uniform linear motion. In FIG. 8, (v _x , v _y ) indicate velocity vectors, and τ ₀ and τ ₁ indicate the time between the current picture (Cur Pic) and two reference pictures (Ref ₀ and Ref ₁ ), respectively. Indicate the distance. (MVx ₀ , MVy ₀ ) indicates a motion vector corresponding to the reference picture Ref ₀ , and (MVx ₁ , MVy ₁ ) indicates a motion vector corresponding to the reference picture Ref ₁ .

At this time, under the assumption of uniform linear motion of the velocity vector (v _x , v _y ), (MV _{x 0} , MV y ₀ ) and (MV _{x 1} , MV y ₁ ) respectively represent (v _x τ ₀ , v _y τ ₀ ) and (-v _x τ ₁ , -v _y τ ₁ ), the following optical flow equation (1) holds.

Here, I ^(k) represents the luminance value of the reference image k (k = 0, 1) after motion compensation. The optical flow equation is: (i) the time derivative of the luminance value, (ii) the product of the horizontal velocity and the horizontal component of the spatial gradient of the reference image, and (iii) the vertical velocity and the spatial gradient of the reference image The product of the vertical components of and the sum of is equal to zero. Based on the combination of the optical flow equation and Hermite interpolation, a motion vector in units of blocks obtained from a merge list or the like is corrected in units of pixels.

Note that the motion vector may be derived on the decoding device side by a method different from the derivation of the motion vector based on a model assuming uniform linear motion. For example, motion vectors may be derived on a subblock basis based on motion vectors of a plurality of adjacent blocks.

Here, a mode for deriving a motion vector in units of sub blocks based on motion vectors of a plurality of adjacent blocks will be described. This mode is sometimes referred to as affine motion compensation prediction mode.

FIG. 9A is a diagram for describing derivation of a motion vector in units of sub blocks based on motion vectors of a plurality of adjacent blocks. In FIG. 9A, the current block includes sixteen 4 × 4 subblocks. Here, the motion vector v ₀ of the upper left corner control point of the current block is derived based on the motion vector of the adjacent block, and the motion vector v ₁ of the upper right corner control point of the current block is derived based on the motion vector of the adjacent subblock Be done. Then, using the two motion vectors v ₀ and v ₁ , the motion vector (v _x , v _y ) of each sub block in the current block is derived according to the following equation (2).

Here, x and y indicate the horizontal position and the vertical position of the sub block, respectively, and w indicates a predetermined weighting factor.

In such an affine motion compensation prediction mode, the derivation method of the motion vector of the upper left and upper right control points may include several different modes. Information indicating such an affine motion compensation prediction mode (for example, called an affine flag) is signaled at the CU level. Note that the signaling of the information indicating this affine motion compensation prediction mode need not be limited to the CU level, and other levels (eg, sequence level, picture level, slice level, tile level, CTU level or subblock level) ) May be.

[Prediction control unit]
The prediction control unit 128 selects one of the intra prediction signal and the inter prediction signal, and outputs the selected signal as a prediction signal to the subtraction unit 104 and the addition unit 116.

Here, an example in which the motion vector of the current picture to be encoded is derived by the merge mode will be described. FIG. 9B is a diagram for describing an overview of motion vector derivation processing in the merge mode.

First, a predicted MV list in which candidates for predicted MV are registered is generated. As the prediction MV candidate, the position of the coding target block in the coded reference picture, which is the MV of the plurality of coded blocks located in the spatial periphery of the coding target block, is projected Temporally adjacent prediction MV which is an MV possessed by a nearby block, joint prediction MV which is an MV generated by combining spatially adjacent prediction MV and MVs of temporally adjacent prediction MV, and zero prediction MV whose value is MV, etc. There is.

Next, one prediction MV is selected from among the plurality of prediction MVs registered in the prediction MV list, and it is determined as the MV of the current block.

Furthermore, in the variable-length coding unit, merge_idx, which is a signal indicating which prediction MV has been selected, is described in the stream and encoded.

Note that the prediction MVs registered in the prediction MV list described in FIG. 9B are an example, and the number is different from the number in the drawing, or the configuration does not include some types of the prediction MV in the drawing, It may have a configuration in which prediction MVs other than the type of prediction MV in the drawing are added.

The final MV may be determined by performing the DMVR process described later using the MV of the coding target block derived in the merge mode.

Here, an example in which the MV is determined using the DMVR process will be described.

FIG. 9C is a conceptual diagram for describing an overview of DMVR processing.

First, with the optimum MVP set as the processing target block as a candidate MV, according to the candidate MV, a first reference picture which is a processed picture in the L0 direction and a second reference picture which is a processed picture in the L1 direction To generate a template by averaging each reference pixel.

Next, using the template, the regions around candidate MVs of the first reference picture and the second reference picture are respectively searched, and the MV with the lowest cost is determined as the final MV. The cost value is calculated using the difference value between each pixel value of the template and each pixel value of the search area, the MV value, and the like.

The outline of the process described here is basically common to the encoding apparatus and the decoding apparatus.

Note that even if the process is not a process described here, another process may be used as long as the process can search for the periphery of the candidate MV and derive a final MV.

Here, a mode in which a predicted image is generated using LIC processing will be described.

FIG. 9D is a diagram for describing an outline of a predicted image generation method using luminance correction processing by LIC processing.

First, an MV for obtaining a reference image corresponding to a current block to be coded is derived from a reference picture which is a coded picture.

Next, for the block to be encoded, reference is made using the luminance pixel values of the left adjacent and upper adjacent encoded peripheral reference areas and the luminance pixel values at equivalent positions in the reference picture specified by MV. Information indicating how the luminance value has changed between the picture and the picture to be encoded is extracted to calculate a luminance correction parameter.

By performing luminance correction processing on a reference image in a reference picture designated by MV using the luminance correction parameter, a predicted image for a block to be encoded is generated.

The shape of the peripheral reference area in FIG. 9D is an example, and other shapes may be used.

Further, although the process of generating a predicted image from one reference picture has been described here, the same applies to a case where a predicted image is generated from a plurality of reference pictures, and is similar to the reference image acquired from each reference picture. After performing luminance correction processing by a method, a predicted image is generated.

As a method of determining whether to apply the LIC process, for example, there is a method using lic_flag which is a signal indicating whether to apply the LIC process. As a specific example, in the encoding apparatus, it is determined whether or not the encoding target block belongs to the area in which the luminance change occurs, and when it belongs to the area in which the luminance change occurs, as lic_flag A value of 1 is set and encoding is performed by applying LIC processing, and when not belonging to an area where a luminance change occurs, a value of 0 is set as lic_flag and encoding is performed without applying the LIC processing. . On the other hand, the decoding apparatus decodes lic_flag described in the stream to switch whether to apply the LIC processing according to the value and performs decoding.

As another method of determining whether to apply the LIC process, for example, there is also a method of determining according to whether or not the LIC process is applied to the peripheral block. As a specific example, when the encoding target block is in merge mode, whether or not the surrounding encoded blocks selected in the derivation of the MV in merge mode processing are encoded by applying LIC processing According to the result, whether to apply the LIC process is switched to perform encoding. In the case of this example, the processing in the decoding is completely the same.

[Overview of Decryption Device]
Next, an outline of a decoding apparatus capable of decoding the coded signal (coded bit stream) output from the above coding apparatus 100 will be described. FIG. 10 is a block diagram showing a functional configuration of decoding apparatus 200 according to Embodiment 1. The decoding device 200 is a moving image / image decoding device that decodes a moving image / image in units of blocks.

As shown in FIG. 10, the decoding apparatus 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse conversion unit 206, an addition unit 208, a block memory 210, a loop filter unit 212, and a frame memory 214. , An intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.

The decoding device 200 is realized by, for example, a general-purpose processor and a memory. In this case, when the processor executes the software program stored in the memory, the processor determines whether the entropy decoding unit 202, the inverse quantization unit 204, the inverse conversion unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216 functions as an inter prediction unit 218 and a prediction control unit 220. In addition, the decoding apparatus 200 is a dedicated unit corresponding to the entropy decoding unit 202, the inverse quantization unit 204, the inverse conversion unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220. And one or more electronic circuits.

Each component included in the decoding device 200 will be described below.

[Entropy decoder]
The entropy decoding unit 202 entropy decodes the coded bit stream. Specifically, the entropy decoding unit 202 performs arithmetic decoding, for example, from a coded bit stream to a binary signal. Then, the entropy decoding unit 202 debinarizes the binary signal. Thereby, the entropy decoding unit 202 outputs the quantization coefficient to the dequantization unit 204 in block units.

[Inverse quantization unit]
The inverse quantization unit 204 inversely quantizes the quantization coefficient of the block to be decoded (hereinafter referred to as a current block), which is an input from the entropy decoding unit 202. Specifically, the dequantization part 204 dequantizes the said quantization coefficient about each of the quantization coefficient of a current block based on the quantization parameter corresponding to the said quantization coefficient. Then, the dequantization unit 204 outputs the dequantized quantization coefficient (that is, transform coefficient) of the current block to the inverse transformation unit 206.

[Inverse converter]
The inverse transform unit 206 restores the prediction error by inversely transforming the transform coefficient that is the input from the inverse quantization unit 204.

For example, when the information deciphered from the coded bit stream indicates that the EMT or AMT is applied (for example, the AMT flag is true), the inverse transform unit 206 determines the current block based on the deciphered transformation type information. Inverse transform coefficients of

Also, for example, when the information deciphered from the coded bit stream indicates that the NSST is to be applied, the inverse transform unit 206 applies inverse retransformation to the transform coefficients.

[Adder]
The addition unit 208 adds the prediction error, which is the input from the inverse conversion unit 206, and the prediction sample, which is the input from the prediction control unit 220, to reconstruct the current block. Then, the adding unit 208 outputs the reconstructed block to the block memory 210 and the loop filter unit 212.

[Block memory]
The block memory 210 is a storage unit for storing a block within a picture to be decoded (hereinafter referred to as a current picture) which is a block referred to in intra prediction. Specifically, the block memory 210 stores the reconstructed block output from the adding unit 208.

[Loop filter section]
The loop filter unit 212 applies a loop filter to the block reconstructed by the adding unit 208, and outputs the filtered reconstructed block to the frame memory 214 and a display device or the like.

If the information indicating on / off of ALF read from the encoded bit stream indicates that ALF is on, one filter is selected from the plurality of filters based on the local gradient direction and activity, The selected filter is applied to the reconstruction block.

[Frame memory]
The frame memory 214 is a storage unit for storing a reference picture used for inter prediction, and may be referred to as a frame buffer. Specifically, the frame memory 214 stores the reconstructed block filtered by the loop filter unit 212.

[Intra prediction unit]
The intra prediction unit 216 refers to a block in the current picture stored in the block memory 210 to perform intra prediction based on the intra prediction mode read from the coded bit stream, thereby generating a prediction signal (intra prediction Signal). Specifically, the intra prediction unit 216 generates an intra prediction signal by performing intra prediction with reference to samples (for example, luminance value, color difference value) of a block adjacent to the current block, and performs prediction control on the intra prediction signal. Output to unit 220.

When the intra prediction mode that refers to the luminance block is selected in the intra prediction of the chrominance block, the intra prediction unit 216 may predict the chrominance component of the current block based on the luminance component of the current block. .

Also, when the information read from the coded bit stream indicates the application of PDPC, the intra prediction unit 216 corrects the pixel value after intra prediction based on the gradient of reference pixels in the horizontal / vertical directions.

[Inter prediction unit]
The inter prediction unit 218 predicts the current block with reference to the reference picture stored in the frame memory 214. The prediction is performed in units of the current block or subblocks (for example, 4 × 4 blocks) in the current block. For example, the inter prediction unit 218 generates an inter prediction signal of the current block or sub block by performing motion compensation using motion information (for example, a motion vector) read from the coded bit stream, and generates an inter prediction signal. It is output to the prediction control unit 220.

When the information deciphered from the coded bit stream indicates that the OBMC mode is applied, the inter prediction unit 218 determines not only the motion information of the current block obtained by the motion search but also the motion information of the adjacent block. Use to generate an inter prediction signal.

Also, in the case where the information deciphered from the coded bit stream indicates that the FRUC mode is applied, the inter prediction unit 218 is configured to follow the method of pattern matching deciphered from the coded stream (bilateral matching or template matching). Motion information is derived by performing motion search. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

In addition, when the BIO mode is applied, the inter prediction unit 218 derives a motion vector based on a model assuming uniform linear motion. Also, in the case where the information deciphered from the coded bit stream indicates that the affine motion compensation prediction mode is applied, the inter prediction unit 218 performs motion vectors in units of sub blocks based on motion vectors of a plurality of adjacent blocks. Derive

[Prediction control unit]
The prediction control unit 220 selects one of the intra prediction signal and the inter prediction signal, and outputs the selected signal to the addition unit 208 as a prediction signal.

[Transform process in the coding apparatus, quantization process and coding process]
Next, the conversion processing, quantization processing and coding processing performed by the conversion unit 106, the quantization unit 108 and the entropy coding unit 110 of the coding apparatus 100 configured as described above are specifically described with reference to the drawings. Explain to.

FIG. 11 is a flowchart illustrating an example of the conversion process, the quantization process, and the encoding process according to the first embodiment. Each step shown in FIG. 11 is performed by the transform unit 106, the quantization unit 108 or the entropy coding unit 110 of the coding apparatus 100 according to the first embodiment.

First, the transform unit 106 performs a linear transformation from the residual of the current block to the primary coefficient (S101). The linear transformation is, for example, a Separable transformation. Specifically, the linear transformation is, for example, DCT or DST.

Next, the conversion unit 106 determines whether secondary conversion is to be performed on the primary coefficient (S102). That is, the transformation unit 106 determines whether or not to apply the quadratic transformation to the encoding target block. For example, the conversion unit 106 determines whether or not to perform the secondary conversion based on the cost based on the difference between the original image and the reconstructed image and / or the code amount. In addition, determination of whether to perform secondary conversion is not limited to determination based on such a cost. For example, whether or not to perform secondary conversion may be determined based on a prediction mode, a block size, a picture type, or any combination thereof.

Here, when it is determined that the secondary conversion is not to be performed (No in S102), the quantization unit 108 performs a first quantization on the primary coefficient to calculate a quantized primary coefficient (S103). . The first quantization is a weighted quantization using a first quantization matrix. The first quantization uses a quantization step that is weighted per coefficient by the first quantization matrix. The first quantization matrix is a weight matrix for adjusting the size of the quantization step for each coefficient. The size of the first quantization matrix matches the size of the current block. That is, the number of components of the first quantization matrix matches the number of coefficients of the current block.

On the other hand, when it is determined that secondary conversion is to be performed (Yes in S102), the conversion unit 106 performs secondary conversion from the primary coefficient to the secondary coefficient (S104). In quadratic transformation, a basis different from that of the linear transformation is used. For example, the quadratic transformation is a non-separable transformation. The bases used in the quadratic transformation are, for example, predefined in the standard.

Thereafter, the quantization unit 108 performs second quantization different from the first quantization on the secondary coefficient to calculate a quantized secondary coefficient (S105). The second quantization different from the first quantization means that the parameter used for the quantization or the quantization method is different between the first quantization and the second quantization. Parameters used for quantization are, for example, quantization matrices or quantization parameters.

In the present embodiment, the second quantization differs from the first quantization in the quantization parameter used for quantization. Specifically, the second quantization is a weighted quantization using a second quantization matrix different from the first quantization matrix. The second quantization uses a quantization step that is weighted on a coefficient-by-coefficient basis by the second quantization matrix.

The second quantization matrix is a weight matrix for adjusting the size of the quantization step for each coefficient. The second quantization matrix has component values different from the first quantization matrix. The size of the second quantization matrix matches the size of the current block. That is, the number of components of the second quantization matrix matches the number of coefficients of the current block.

The entropy coding unit 110 generates a coded bit stream by entropy coding the quantized primary coefficient or the quantized secondary coefficient (S106). At this time, the entropy coding unit 110 writes the first quantization matrix and the second quantization matrix in the coded bit stream.

If the secondary transformation is performed only on the one or more first primary coefficients included in the primary coefficients in the encoding target block, the secondary transformation may be performed on the one or more first primary coefficients to be implemented. One or more of the second quantization matrix corresponding to one or more second primary coefficients for which only one or more first component values of the corresponding second quantization matrix are written to the coded bit stream and no secondary transformation is performed Each of the second component values may not be written to the coded bit stream and may be common to the corresponding component values of the first quantization matrix. That is, each of the one or more second component values of the second quantization matrix may correspond to a corresponding component value of the first quantization matrix. Note that one or more first primary coefficients are, for example, coefficients in a low frequency region, and one or more second primary coefficients are, for example, coefficients in a high frequency region.

In addition, the entropy coding unit 110 may write information indicating whether or not to apply the secondary transformation to the coding target block in the coding bit stream.

The positions in the coded bit stream of the first quantization matrix and the second quantization matrix are not particularly limited. For example, as shown in FIG. 12, the first quantization matrix and the second quantization matrix are (i) video parameter set (VPS), (ii) sequence parameter set (SPS), (iii) picture parameter set (PPS) ), (Iv) slice header, or (v) video system configuration parameters.

As described above, in the present embodiment, different quantization is performed in the case where the secondary conversion is performed and the case where the secondary conversion is not performed. That is, the quantization unit 108 switches the first quantization and the second quantization based on application / non-application of the secondary transformation to the encoding target block. In particular, in the present embodiment, different quantization matrices are used in the case where the secondary conversion is performed and the case where the secondary conversion is not performed. That is, in the present embodiment, the quantization unit 108 performs switching by switching the first quantization matrix and the second quantization matrix based on application / non-application of the secondary transformation to the encoding target block. .

[Decoding processing in the decoding apparatus, inverse quantization processing and inverse transformation processing]
Next, the decoding process, the inverse quantization process, and the inverse transformation process performed by entropy decoding section 202, inverse quantization section 204, and inverse transformation section 206 of decoding apparatus 200 according to the present embodiment will be specifically described with reference to the drawings. Explain to.

FIG. 13 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the first embodiment. Each step shown in FIG. 13 is performed by the entropy decoding unit 202, the inverse quantization unit 204, or the inverse transform unit 206.

First, the entropy decoding unit 202 entropy decodes the coded quantization coefficient of the current block to be decoded from the coded bit stream (S201). The quantization coefficient decoded here is a quantized first-order coefficient or a quantized second-order coefficient. Also, here, the entropy decoding unit 202 further interprets the first quantization matrix and the second quantization matrix from the coded bit stream. When the inverse quadratic transform is performed only on one or more first quadratic coefficients included in the quadratic coefficients in the block to be decoded, the one or more first quadratic transforms are performed. Decoding only one or more first component values of the second quantization matrix corresponding to secondary coefficients from the encoded bit stream, and second quantum corresponding to one or more second secondary coefficients for which inverse quadratic transformation is not performed Each of the one or more second component values of the quantization matrix may be common to the corresponding component value of the first quantization matrix. That is, each of the one or more second component values of the second quantization matrix may correspond to a corresponding component value of the first quantization matrix. Furthermore, the entropy decoding unit 202 may read and interpret, from the encoded bit stream, information indicating whether to apply the inverse quadratic transform to the block to be decoded.

The inverse transform unit 206 determines whether to perform the inverse quadratic transform based on the coded bit stream (S202). That is, the inverse transformation unit 206 determines whether to apply the inverse quadratic transformation to the block to be decoded. For example, the inverse transformation unit 206 determines whether or not to perform the inverse quadratic transformation based on the information indicating whether to apply the inverse quadratic transformation that is deciphered from the encoded bit stream.

Here, when it is determined that the inverse quadratic transformation is not to be performed (No in S202), the inverse quantization unit 204 performs the first inverse quantization on the decoded quantization coefficient to obtain the primary coefficient. Calculate (S203). The first inverse quantization is inverse quantization of the first quantization in the encoding device 100. In the present embodiment, the first inverse quantization is a weighted inverse quantization using a first quantization matrix.

On the other hand, when it is determined that the inverse quadratic transformation is to be performed (Yes in S202), the inverse quantization unit 204 performs second inverse quantization different from the first inverse quantization on the decoded quantization coefficient. By doing this, secondary coefficients are calculated (S204). The second inverse quantization is inverse quantization of the second quantization in the encoding device 100. In the present embodiment, the second dequantization is a weighted dequantization using a second quantization matrix. After that, the inverse transformation unit 206 performs inverse quadratic transformation from the secondary coefficient calculated by the second inverse quantization to the primary coefficient (S205). The inverse quadratic transform is an inverse transform of the quadratic transform in the encoding device 100.

The inverse transformation unit 206 performs inverse linear transformation of the primary coefficient obtained by inverse quadratic transformation or first inverse quantization to the residual of the block to be decoded (S206). The inverse linear transformation is an inverse transformation of the linear transformation in the encoding device 100.

As described above, in the present embodiment, different inverse quantization is performed depending on whether the inverse quadratic transformation is performed or not. That is, the inverse quantization unit 204 switches the first inverse quantization and the second inverse quantization based on application / non-application of the inverse quadratic transformation to the block to be decoded. In particular, in the present embodiment, different quantization matrices are used when performing the inverse quadratic transformation and when not performing the inverse quadratic transformation. That is, in the present embodiment, the inverse quantization unit 204 performs the inverse quantization by switching the first quantization matrix and the second quantization matrix based on application / non-application of the inverse quadratic transformation.

[Effects, etc.]
As described above, according to encoding apparatus 100 and decoding apparatus 200 according to the present embodiment, different quantization / inverse quantization depending on application / non-application of secondary transformation / inverse quadratic transformation to current block It can be performed. The second-order coefficient which is quadratically converted from the first-order coefficient represented in the first space is to be expressed in the second-order space other than the first-order space. Therefore, even if the quantization / inverse quantization for the first-order coefficient is applied to the second-order coefficient, it is difficult to improve the coding efficiency while suppressing the deterioration of the subjective image quality. For example, the quantization for increasing the loss of the high frequency range component to reduce the loss of the low frequency range component in order to suppress the deterioration of the subjective image quality and to increase the coding efficiency is the first order space and the second order space. It differs in the next space. Therefore, by performing different quantization / inverse quantization depending on application / non-application of secondary transformation / inverse quadratic transformation to the current block, compared to the case where common quantization / inverse quantization is performed. The coding efficiency can be improved while suppressing the degradation of the subjective image quality.

Moreover, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, weighted quantization / inverse quantization using the first quantization matrix is performed as the first quantization / first inverse quantization. Can. Furthermore, weighted quantization / inverse quantization using a second quantization matrix different from the first quantization matrix can be performed as the second quantization / second inverse quantization. Therefore, the first quantization matrix corresponding to the primary space can be used for the quantization / inverse quantization for the primary coefficients, and the secondary space corresponds to the quantization / inverse quantization for the secondary coefficients A second quantization matrix can be used. Therefore, in both the application and non-application of the quadratic transform / inverse quadratic transform, it is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Moreover, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, the first quantization matrix and the second quantization matrix can be included in the encoded bit stream. Therefore, it is possible to adaptively determine the first quantization matrix and the second quantization matrix according to the original image, and it is possible to improve the coding efficiency while suppressing the deterioration of the subjective image quality.

In the present embodiment, the first quantization matrix and the second quantization matrix are included in the coded bit stream, but the present invention is not limited to this. For example, the first quantization matrix and the second quantization matrix may be transmitted from the encoder to the decoder separately from the coded bit stream. Also, for example, the first quantization matrix and the second quantization matrix may be predefined in the standardization standard. At this time, the first quantization matrix and the second quantization matrix may be called a default matrix. Also, for example, the first quantization matrix and the second quantization matrix may be selected from among a plurality of default matrices based on a given profile or level or the like.

Thereby, the first quantization matrix and the second quantization matrix may not be included in the coded bit stream, and the code amount for the first quantization matrix and the second quantization matrix can be reduced.

In the present embodiment, although the case where one base is fixedly used in the quadratic conversion / inverse quadratic conversion has been described, the present invention is not limited to this. For example, in the quadratic conversion / inverse quadratic conversion, a plurality of predetermined bases may be selectively used. In this case, for example, the coded bit stream may include a plurality of second quantization matrices corresponding to a plurality of bases. And, in the second quantization / second inverse quantization, even if the second quantization matrix corresponding to the basis used for the secondary transformation / inverse quadratic transformation is selected from the plurality of second quantization matrices Good.

Thereby, the second quantization / the second inverse quantization can be performed using the second quantization matrix corresponding to the basis used in the second transformation / the inverse quadratic conversion. Depending on the basis used in the quadratic transformation / inverse quadratic transformation, the features of the quadratic space representing the quadratic coefficients are different. Therefore, by performing the second quantization / the second inverse quantization using the second quantization matrix corresponding to the basis used in the secondary transformation / inverse quadratic transformation, the quantization matrix further corresponding to the secondary space Can be used to perform second quantization / second inverse quantization, and coding efficiency can be improved while suppressing deterioration in subjective image quality.

Second Embodiment
Next, the second embodiment will be described. The present embodiment is different from the first embodiment in that a second quantization matrix used in the second quantization is derived from the first quantization matrix used in the first quantization. The present embodiment will be specifically described below with reference to the drawings, focusing on differences from the first embodiment.

[Transform process in the coding apparatus, quantization process and coding process]
The conversion processing, quantization processing and coding processing performed by the conversion unit 106, the quantization unit 108 and the entropy coding unit 110 of the coding apparatus 100 according to Embodiment 2 will be specifically described with reference to the drawings.

FIG. 14 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the second embodiment. In FIG. 14, the processing substantially the same as that of FIG.

In the present embodiment, after the secondary conversion is performed (S104), the quantization unit 108 derives a second quantization matrix from the first quantization matrix (S111). For example, the quantization unit 108 derives a second quantization matrix by applying a secondary transformation to the first quantization matrix. That is, the quantization unit 108 transforms the first quantization matrix using the basis used for the secondary transformation of the current block.

If the secondary transformation is performed only on the one or more first primary coefficients included in the primary coefficients in the encoding target block, the secondary transformation may be performed on the one or more first primary coefficients to be implemented. One or more of the second quantization matrix corresponding to one or more second primary coefficients for which one or more first component values of the corresponding second quantization matrix are derived from the first quantization matrix and secondary transformation is not performed Each of the second component values of may be common to the corresponding component value of the first quantization matrix. That is, each of the one or more second component values of the second quantization matrix may correspond to a corresponding component value of the first quantization matrix.

The quantization unit 108 calculates a quantized secondary coefficient by performing second quantization on the secondary coefficient (S105). In this second quantization, the second quantization matrix derived in step S111 is used.

The entropy coding unit 110 generates a coded bit stream by entropy coding the quantized primary coefficient or the quantized secondary coefficient (S112). Furthermore, in the present embodiment, the entropy coding unit 110 writes the first quantization matrix to the coded bit stream. Conversely, the entropy coding unit 110 does not write the second quantization matrix to the coded bit stream.

Thus, the quantization unit 108 performs switching by switching between the first quantization matrix and the second quantization matrix based on application / non-application of the secondary transformation to the encoding target block. At this time, the quantization unit 108 derives a second quantization matrix from the first quantization matrix.

[Decoding processing in the decoding apparatus, inverse quantization processing and inverse transformation processing]
Next, the decoding process, the inverse quantization process, and the inverse transformation process performed by entropy decoding section 202, inverse quantization section 204, and inverse transformation section 206 of decoding apparatus 200 according to the present embodiment will be specifically described with reference to the drawings. Explain to.

FIG. 15 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the second embodiment. In FIG. 15, processes substantially the same as those in FIG. 13 are assigned the same reference numerals and descriptions thereof will be omitted as appropriate.

First, the entropy decoding unit 202 decodes the coded quantization coefficient included in the coded bit stream (S211). At this time, the entropy decoding unit 202 deciphers the first quantization matrix from the coded bit stream.

As in the first embodiment, the inverse transform unit 206 determines whether to perform the inverse quadratic transform based on the coded bit stream (S202). Here, when it is determined that the inverse quadratic transformation is not to be performed (No in S202), the inverse quantization unit 204 performs the first inverse quantization on the decoded quantization coefficient as in the first embodiment. (S203).

On the other hand, when it is determined that the inverse quadratic transformation is to be performed (Yes in S202), the inverse quantization unit 204 derives a second quantization matrix from the first quantization matrix (S212). Specifically, the inverse quantization unit 204 derives the second quantization matrix in the same manner as the encoding device 100. For example, the inverse quantization unit 204 derives a second quantization matrix by applying a quadratic transform to the first quantization matrix. That is, the inverse quantization unit 204 transforms the first quantization matrix using the basis used for the secondary transformation of the block to be decoded. When the inverse quadratic transform is performed only on one or more first quadratic coefficients included in the quadratic coefficients in the block to be decoded, the one or more first quadratic transforms are performed. One or more first component values of the second quantization matrix corresponding to the second order coefficients derived from the first quantization matrix, and a second corresponding to the one or more second second order coefficients for which an inverse quadratic transformation is not performed Each of the one or more second component values of the quantization matrix may be common to the corresponding component value of the first quantization matrix. That is, each of the one or more second component values of the second quantization matrix may correspond to a corresponding component value of the first quantization matrix.

Thereafter, the process of step S204 and subsequent steps is performed.

As described above, the inverse quantization unit 204 performs the inverse quantization by switching the first quantization matrix and the second quantization matrix based on application / non-application of the inverse quadratic transformation to the decoding target block. At this time, the inverse quantization unit 204 derives a second quantization matrix from the first quantization matrix. Therefore, even if the second quantization matrix is not included in the coded bit stream, the decoding apparatus 200 can perform the second inverse quantization.

[Effects, etc.]
As described above, according to encoding apparatus 100 and decoding apparatus 200 according to the present embodiment, the second quantization matrix can be derived from the first quantization matrix. Therefore, since it is not necessary to transmit the second quantization matrix to the decoding device, the coding efficiency can be improved.

Also, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, the second quantization matrix can be derived by applying the secondary transformation to the first quantization matrix. Therefore, the first quantization matrix corresponding to the primary space can be converted to the second quantization matrix corresponding to the secondary space, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

(Modification of Embodiment 2)
In the present embodiment, as a method of deriving the second quantization matrix, an example in which the second transformation is directly applied to the first quantization matrix has been described, but the present invention is not limited thereto. Hereinafter, another example of the method of deriving the second quantization matrix will be described with reference to FIG.

FIG. 16 is a flowchart showing an example of derivation processing of the second quantization matrix in the modification of the second embodiment. This flowchart shows an example of the process of step S111 of FIG. 14 and step S212 of FIG.

In FIG. 16, the quantization unit 108 or the inverse quantization unit 204 derives a third quantization matrix from the first quantization matrix (S301). At this time, each component value of the third quantization matrix is larger as the corresponding component value of the first quantization matrix is smaller. That is, as the component values of the first quantization matrix increase, the corresponding component values of the third quantization matrix decrease. In other words, the component values of the first quantization matrix and the component values of the third quantization matrix have a monotonically decreasing relationship. For example, each component value of the third quantization matrix is the reciprocal of the corresponding component value of the first quantization matrix.

Next, the quantization unit 108 or the inverse quantization unit 204 derives a fourth quantization matrix by applying a secondary transformation to the third quantization matrix (S302). That is, the quantization unit 108 or the inverse quantization unit 204 transforms the third quantization matrix using the basis used for the secondary transformation of the current block.

Finally, the quantization unit 108 or the inverse quantization unit 204 derives the fifth quantization matrix from the fourth quantization matrix as a second quantization matrix (S303). At this time, each component value of the fifth quantization matrix is larger as a corresponding component value of the fourth quantization matrix is smaller. That is, as the component values of the fourth quantization matrix increase, the corresponding component values of the fifth quantization matrix decrease. In other words, the component values of the fourth quantization matrix and the component values of the fifth quantization matrix have a monotonically decreasing relationship. For example, each component value of the fifth quantization matrix is the reciprocal of the corresponding component value of the fourth quantization matrix.

By deriving the second quantization matrix as described above, it is possible to reduce the influence of the rounding error at the time of secondary conversion on the component having a relatively small value included in the first quantization matrix. That is, it is possible to reduce the influence of the rounding error on the value of the component applied to the coefficient whose loss is desired to be reduced in order to suppress the deterioration of the subjective image quality. Therefore, the deterioration of the subjective image quality can be further suppressed.

Also, as each component value of the third quantization matrix / the fifth quantization matrix, the reciprocal of the corresponding component value of the first quantization matrix / the fourth quantization matrix can be used. Therefore, component values can be derived by simple calculation, and processing load or processing time for deriving the second quantization matrix can be reduced.

Third Embodiment
Next, the third embodiment will be described. The present embodiment is different from the above-described first embodiment in that secondary coefficients are quantized without using a quantization matrix when secondary conversion is performed. The present embodiment will be specifically described below with reference to the drawings, focusing on differences from the first embodiment.

[Transform process in the coding apparatus, quantization process and coding process]
The conversion processing, quantization processing, and coding processing performed by the conversion unit 106, the quantization unit 108, and the entropy coding unit 110 of the coding apparatus 100 according to Embodiment 3 will be specifically described with reference to the drawings.

FIG. 17 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the third embodiment. In FIG. 17, the processing substantially the same as that of FIG.

After the secondary conversion from the primary coefficient to the secondary coefficient is performed (S104), the quantization unit 108 performs quantization 2 by performing second quantization different from the first quantization on the secondary coefficient. The next coefficient is calculated (S121). In the present embodiment, the second quantization is unweighted quantization that does not use a quantization matrix. That is, the second quantization divides each secondary coefficient in a common quantization step to the secondary coefficient of the current block. The common quantization step is derived from the quantization parameters for the block to be coded. Specifically, the common quantization step is one fixed constant for all secondary coefficients of the current block. That is, the common quantization step is a constant that does not depend on the position or order of secondary coefficients.

As described above, in the present embodiment, the quantization unit 108 switches weighted quantization and non-weighted quantization based on application / non-application of the secondary transformation to the coding target block.

[Decoding processing in the decoding apparatus, inverse quantization processing and inverse transformation processing]
Next, the decoding process, the inverse quantization process, and the inverse transformation process performed by the entropy decoding unit 202, the inverse quantization unit 204, and the inverse transformation unit 206 of the decoding apparatus 200 according to Embodiment 3 will be specifically described with reference to the drawings. Explain to.

FIG. 18 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the third embodiment. In FIG. 18, the processing substantially the same as that of FIG.

When it is determined that the inverse quadratic transform is to be performed (Yes in S202), the inverse quantization unit 204 performs a second inverse quantization different from the first inverse quantization on the decoded quantization coefficient. A quadratic coefficient is calculated (S221). The second inverse quantization is inverse quantization of the second quantization in the encoding device 100. In the present embodiment, the second inverse quantization is unweighted inverse quantization that does not use a quantization matrix.

As described above, in the present embodiment, the inverse quantization unit 204 switches between weighted inverse quantization and non-weighted inverse quantization based on application / non-application of the inverse quadratic transform to the block to be decoded.

[Effects, etc.]
As described above, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, unweighted quantization / inverse quantization can be used as the second quantization / second inverse quantization. Therefore, for the second quantization while preventing the deterioration of the subjective image quality by using the first quantization matrix for the first quantization / first inverse quantization in the second quantization / second inverse quantization. The coding or derivation process of the quantization matrix can be omitted.

Embodiment 4
Next, the fourth embodiment will be described. The present embodiment is different from the third embodiment in that each primary coefficient obtained by linear transformation is multiplied by a corresponding component value of a weight matrix and then transformation is performed. Hereinafter, the present embodiment will be specifically described with reference to the drawings, focusing on differences from the above-described third embodiment.

[Transform process in the coding apparatus, quantization process and coding process]
The conversion processing, quantization processing, and coding processing performed by the conversion unit 106, the quantization unit 108, and the entropy coding unit 110 of the coding apparatus 100 according to the fourth embodiment will be specifically described with reference to the drawings.

FIG. 19 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the fourth embodiment. FIG. 20 is a diagram for describing an example of secondary conversion in the fourth embodiment. In FIG. 19, processes substantially the same as those in FIG. 17 are assigned the same reference numerals and descriptions thereof will be omitted as appropriate.

If it is determined that secondary conversion is to be performed (Yes in S102), the conversion unit 106 performs secondary conversion from the primary coefficient to the secondary coefficient (S130). Specifically, as shown in FIG. 20, in the secondary conversion, the converting unit 106 calculates weighted primary coefficients by multiplying each of the primary coefficients by the corresponding component value of the weight matrix (S131). . The weighting matrix is a matrix for weighting primary coefficients. Then, the conversion unit 106 converts the weighted primary coefficient into a secondary coefficient (S132). This transformation is, for example, substantially the same as the quadratic transformation of each of the above embodiments, and the weighted primary coefficient is transformed instead of the primary coefficient.

The weight matrix may be derived from the first quantization matrix. In this case, for example, the component values of the weight matrix and the component values of the first quantization matrix may have a monotonically decreasing relationship. Specifically, for example, each component value of the weight matrix may be the reciprocal of the corresponding component value of the first quantization matrix. Thereby, the first quantization matrix for weighting of the quantization step can be converted into a weight matrix for weighting of coefficients.

Also, the weight matrix may be included in the coded bit stream or may be predefined in the standard. Also, in the standard, a plurality of weight matrices may be defined. In this case, the weight matrix may be selected from among a plurality of predefined weight matrices based on a given profile or level or the like.

The quantization unit 108 calculates a quantized secondary coefficient by performing a second quantization different from the first quantization on the secondary coefficient (S121). In the present embodiment, the second quantization is unweighted quantization that does not use a quantization matrix. That is, the second quantization divides each secondary coefficient in a common quantization step to the secondary coefficient of the current block. At this time, the common quantization step may be derived, for example, by the quantization unit 108 from the quantization parameter for the current block.

[Decoding processing in the decoding apparatus, inverse quantization processing and inverse transformation processing]
Next, the decoding process, the inverse quantization process, and the inverse transform process performed by the entropy decoding unit 202, the inverse quantization unit 204, and the inverse transform unit 206 of the decoding apparatus 200 according to the fourth embodiment are specifically described with reference to the drawings. Explain to.

FIG. 21 is a flowchart illustrating an example of the decoding process, the inverse quantization process, and the inverse transform process according to the fourth embodiment. FIG. 22 is a diagram for describing an example of the inverse quadratic conversion in the fourth embodiment. In FIG. 21, processes substantially the same as those in FIG. 18 are given the same reference numerals, and the description will be omitted as appropriate.

When it is determined that the inverse quadratic transform is to be performed (Yes in S202), the inverse quantization unit 204 performs a second inverse quantization different from the first inverse quantization on the decoded quantization coefficient. A quadratic coefficient is calculated (S221). The second inverse quantization is inverse quantization of the second quantization in the encoding device 100. In the present embodiment, the second inverse quantization is unweighted inverse quantization that does not use a quantization matrix. That is, as shown in FIG. 22, the inverse quantization unit 204 calculates secondary coefficients by multiplying each of the quantization coefficients by the common quantization step in the quantization coefficient of the current block. At this time, the common quantization step may be derived from, for example, quantization parameters for the block to be decoded.

Next, the inverse transformation unit 206 performs inverse quadratic transformation from the secondary coefficient to the primary coefficient (S230). Specifically, as shown in FIG. 22, the inverse transformation unit 206 performs inverse transformation from the secondary coefficient to the weighted primary coefficient (S231). This inverse transformation is an inverse transformation of the transformation (S132) from weighted primary coefficients to secondary coefficients in the encoding device 100.

Furthermore, the inverse transformation unit 206 calculates primary coefficients by dividing each of the weighted primary coefficients by the corresponding component value of the weight matrix (S232). This weight matrix matches the weight matrix used by the coding apparatus 100.

The weight matrix may be derived from the first quantization matrix by the inverse quantization unit 204. In this case, for example, the component values of the weight matrix and the component values of the first quantization matrix may have a monotonically decreasing relationship. For example, each component value of the weight matrix may be the reciprocal of the corresponding component value of the first quantization matrix.

Also, the weight matrix may be included in the coded bit stream or may be predefined in the standard. Also, multiple weight matrices may be predefined in the standard. In this case, the weight matrix may be selected from among a plurality of predefined weight matrices based on a given profile or level or the like.

[Effects, etc.]
As described above, according to encoding apparatus 100 in accordance with the present embodiment, weighted primary coefficients can be calculated by multiplying each of the primary coefficients by the corresponding component value of the weight matrix. Further, according to decoding apparatus 200 in accordance with the present embodiment, primary coefficients can be calculated by dividing each of the weighted primary coefficients by the corresponding component value of the weight matrix. That is, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, weighting relating to quantization can be performed on the primary coefficients before secondary transformation. Therefore, when quadratic transformation / inverse quadratic transformation is applied, quantization / inverse quantization equivalent to weighted quantization / inverse quantization without newly preparing a quantization matrix corresponding to secondary space Can be done. As a result, it is possible to improve the coding efficiency while suppressing the degradation of the subjective image quality.

Moreover, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, the weight matrix can be derived from the first quantization matrix. Therefore, the code amount for the weight matrix can be reduced, and the coding efficiency can be improved while suppressing the degradation of the subjective image quality.

Moreover, according to the encoding apparatus 100 and the decoding apparatus 200 according to the present embodiment, a quantization step common to secondary coefficients of the current block can be derived from the quantization parameter. Therefore, it is not necessary to include new information in the coding stream for the common quantization step, and the code amount for the common quantization step can be reduced.

Fifth Embodiment
Next, the fifth embodiment will be described. The present embodiment is different from each of the above-described embodiments in that the quantization is performed on the primary coefficient before the secondary conversion when the secondary conversion is applied. Hereinafter, the present embodiment will be specifically described with reference to the drawings, focusing on differences from the above-described embodiments.

[Transform process in the coding apparatus, quantization process and coding process]
The conversion processing, quantization processing and coding processing performed by the conversion unit 106, the quantization unit 108 and the entropy coding unit 110 of the coding apparatus 100 according to the fifth embodiment will be specifically described with reference to the drawings.

FIG. 23 is a flowchart illustrating an example of conversion processing, quantization processing, and encoding processing according to the fifth embodiment. In FIG. 23, the processing substantially the same as that of FIG.

When it is determined that the secondary conversion is not to be performed (No in S102), the quantization unit 108 performs a first quantization on the primary coefficient to calculate a first quantized primary coefficient (S141).

On the other hand, when it is determined that secondary conversion is to be performed (Yes in S102), the quantization unit 108 performs second quantization on the primary coefficient to calculate a second quantized primary coefficient (S142). In the present embodiment, the first quantization and the second quantization may be different from each other as in the first to fourth embodiments, or may be the same. That is, in the present embodiment, the same process may be performed using the same quantization matrix in the first quantization and the second quantization. Subsequently, the conversion unit 106 performs secondary conversion from the second quantized primary coefficient to the quantized secondary coefficient (S143).

The entropy coding unit 110 generates a coded bit stream by coding the first quantized primary coefficient or the quantized secondary coefficient (S106).

Thus, in the present embodiment, when the quadratic transform is applied to the coding target block, the second quantization is performed before the quadratic transform. That is, the second quantization is performed on the primary coefficient.

[Decoding processing in the decoding apparatus, inverse quantization processing and inverse transformation processing]
Next, the decoding process, the inverse quantization process, and the inverse transformation process performed by the entropy decoding unit 202, the inverse quantization unit 204, and the inverse transformation unit 206 of the decoding apparatus 200 according to the fifth embodiment are specifically described with reference to the drawings. Explain to.

FIG. 24 is a flowchart illustrating an example of decoding processing, inverse quantization processing, and inverse transform processing according to the fifth embodiment. In FIG. 24, the processing substantially the same as that of FIG.

When it is determined that the inverse quadratic transformation is not to be performed (No in S202), the inverse quantization unit 204 calculates the primary coefficient by performing the first inverse quantization on the decoded quantization coefficient (S241). ). The first inverse quantization is inverse quantization of the first quantization in the encoding device 100.

On the other hand, when it is determined that the inverse quadratic transform is to be performed (Yes in S202), the inverse transform unit 206 performs the inverse quadratic transform to the quantized primary coefficient from the decoded quantization coefficient (S242). The inverse quadratic transform is an inverse transform of the quadratic transform in the encoding device 100. Subsequently, the inverse quantization unit 204 performs second inverse quantization on the quantized primary coefficient to calculate a primary coefficient (S243). The second inverse quantization is inverse quantization of the second quantization in the encoding device 100. Thus, if the second quantization is the same as the first quantization, the second inverse quantization is the same as the first inverse quantization.

Thus, in the present embodiment, when the inverse quadratic transform is applied to the block to be decoded, the second inverse quantization is performed after the inverse quadratic transform. That is, the second inverse quantization is performed on the quantized first-order coefficient.

[Effects, etc.]
As described above, according to encoding apparatus 100 and decoding apparatus 200 according to the present embodiment, quantization can be performed before secondary conversion, so in the case where lossless secondary conversion processing is performed, The next transformation can be removed from the loop of prediction processing. Therefore, the load on the processing pipeline can be reduced. In addition, by performing quantization before secondary conversion, it is also possible to simplify the process because it is not necessary to separate the first quantization matrix and the second quantization matrix.

(Modification)
Although the encoding apparatus and the decoding apparatus according to one or more aspects of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to the embodiments. Without departing from the spirit of the present disclosure, various modifications that can occur to those skilled in the art may be applied to the present embodiment, or a configuration constructed by combining components in different embodiments may be one or more of the present disclosure. It may be included within the scope of the embodiments.

For example, in the second embodiment, although the second quantization matrix is derived after the quadratic transformation or after the determination of the inverse quadratic transformation, the present invention is not limited to this. Derivation of the second quantization matrix may be performed anytime after the first quantization matrix is obtained and before the second quantization / inverse quantization. For example, the second quantization matrix may be derived at the start of encoding or decoding of the current picture including the current block. In this case, the second quantization matrix may not be derived for each block.

In each of the above embodiments, the encoding / decoding of one encoding / decoding target block has been mainly described, but the above-mentioned conversion processing, quantization processing and encoding processing, or decoding processing, inverse quantization processing The inverse transform process can be applied to a plurality of blocks included in the coding / decoding target picture. In this case, the first quantization matrix and the second quantization matrix corresponding to the prediction mode (eg intra prediction or inter prediction), the type of pixel value (eg luminance or chrominance), the size of the block, or any combination thereof It may be used.

In addition, the switching process of the quantization based on application / non-application of the secondary transformation in each said embodiment may be turned on / off in a slice level, a tile level, a CTU level, or CU level. Also, on / off may be determined according to the frame type (I-frame, P-frame, B-frame) and / or the prediction mode.

Moreover, the switching process of quantization based on application / non-application of the secondary conversion in each of the above embodiments may be performed on one or both of the luminance block and the chrominance block.

In each of the above-described embodiments, the determination as to whether or not to perform the secondary conversion is performed after the primary conversion, but is not limited to this. The determination as to whether or not to perform the secondary conversion may be made in advance prior to the processing of the current block.

Furthermore, in the first embodiment, the first quantization matrix and the second quantization matrix may not always be different.

Sixth Embodiment
In each of the above embodiments, each of the functional blocks can usually be realized by an MPU, a memory, and the like. Further, the processing by each of the functional blocks is usually realized by a program execution unit such as a processor reading and executing software (program) recorded in a recording medium such as a ROM. The software may be distributed by downloading or the like, or may be distributed by being recorded in a recording medium such as a semiconductor memory. Of course, it is also possible to realize each functional block by hardware (dedicated circuit).

Also, the processing described in each embodiment may be realized by centralized processing using a single device (system), or may be realized by distributed processing using a plurality of devices. Good. Moreover, the processor that executes the program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

The aspects of the present disclosure are not limited to the above examples, and various modifications are possible, which are also included in the scope of the aspects of the present disclosure.

Furthermore, an application example of the moving picture coding method (image coding method) or the moving picture decoding method (image decoding method) shown in each of the above-described embodiments and a system using the same will be described. The system is characterized by having an image coding apparatus using an image coding method, an image decoding apparatus using an image decoding method, and an image coding / decoding apparatus provided with both. Other configurations in the system can be suitably modified as the case may be.

[Example of use]
FIG. 117 is a diagram showing an overall configuration of a content supply system ex100 for realizing content distribution service. The area for providing communication service is divided into desired sizes, and base stations ex106, ex107, ex108, ex109 and ex110, which are fixed wireless stations, are installed in each cell.

In this content supply system ex100, each device such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 via the Internet service provider ex102 or the communication network ex104 and the base stations ex106 to ex110 on the Internet ex101 Is connected. The content supply system ex100 may connect any of the above-described elements in combination. The respective devices may be connected to each other directly or indirectly via a telephone network, near-field radio, etc., not via the base stations ex106 to ex110 which are fixed wireless stations. Also, the streaming server ex103 is connected to each device such as the computer ex111, the game machine ex112, the camera ex113, the home appliance ex114, and the smartphone ex115 via the Internet ex101 or the like. Also, the streaming server ex103 is connected to a terminal or the like in a hotspot in the aircraft ex117 via the satellite ex116.

A radio access point or a hotspot may be used instead of base stations ex106 to ex110. Also, the streaming server ex103 may be directly connected to the communication network ex104 without the internet ex101 or the internet service provider ex102, or may be directly connected with the airplane ex117 without the satellite ex116.

The camera ex113 is a device capable of shooting a still image such as a digital camera and shooting a moving image. The smartphone ex115 is a smartphone, a mobile phone, a PHS (Personal Handyphone System), or the like compatible with a mobile communication system generally called 2G, 3G, 3.9G, 4G, and 5G in the future.

The home appliance ex118 is a refrigerator or a device included in a home fuel cell cogeneration system.

In the content supply system ex100, when a terminal having a photographing function is connected to the streaming server ex103 through the base station ex106 or the like, live distribution and the like become possible. In live distribution, a terminal (a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal in an airplane ex117, etc.) transmits the still image or moving image content captured by the user using the terminal. The encoding process described in each embodiment is performed, and video data obtained by the encoding and sound data obtained by encoding a sound corresponding to the video are multiplexed, and the obtained data is transmitted to the streaming server ex103. That is, each terminal functions as an image coding apparatus according to an aspect of the present disclosure.

On the other hand, the streaming server ex 103 streams the content data transmitted to the requested client. The client is a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal in the airplane ex117, or the like capable of decoding the above-described encoded data. Each device that receives the distributed data decrypts and reproduces the received data. That is, each device functions as an image decoding device according to an aspect of the present disclosure.

[Distributed processing]
Also, the streaming server ex103 may be a plurality of servers or a plurality of computers, and may process, record, or distribute data in a distributed manner. For example, the streaming server ex103 may be realized by a CDN (Contents Delivery Network), and content delivery may be realized by a network connecting a large number of edge servers distributed around the world and the edge servers. In the CDN, physically close edge servers are dynamically assigned according to clients. The delay can be reduced by caching and distributing the content to the edge server. In addition, when there is an error or when the communication status changes due to an increase in traffic etc., processing is distributed among multiple edge servers, or the distribution subject is switched to another edge server, or a portion of the network where a failure has occurred. Since the delivery can be continued bypassing, high-speed and stable delivery can be realized.

In addition to the distributed processing of distribution itself, each terminal may perform encoding processing of captured data, or may perform processing on the server side, or may share processing with each other. As an example, generally in the encoding process, a processing loop is performed twice. In the first loop, the complexity or code amount of the image in frame or scene units is detected. In the second loop, processing is performed to maintain the image quality and improve the coding efficiency. For example, the terminal performs a first encoding process, and the server receiving the content performs a second encoding process, thereby improving the quality and efficiency of the content while reducing the processing load on each terminal. it can. In this case, if there is a request to receive and decode in substantially real time, the first encoded data made by the terminal can also be received and reproduced by another terminal, enabling more flexible real time delivery Become.

As another example, the camera ex 113 or the like extracts a feature amount from an image, compresses data relating to the feature amount as metadata, and transmits the data to the server. The server performs compression according to the meaning of the image, for example, determining the importance of the object from the feature amount and switching the quantization accuracy. Feature amount data is particularly effective in improving the accuracy and efficiency of motion vector prediction at the time of second compression in the server. Also, the terminal may perform simple coding such as VLC (variable length coding) and the server may perform coding with a large processing load such as CABAC (context adaptive binary arithmetic coding method).

As still another example, in a stadium, a shopping mall, or a factory, there may be a plurality of video data in which substantially the same scenes are shot by a plurality of terminals. In this case, for example, a unit of GOP (Group of Picture), a unit of picture, or a tile into which a picture is divided, using a plurality of terminals for which photographing was performed and other terminals and servers which are not photographing as necessary. The encoding process is allocated in units, etc., and distributed processing is performed. This reduces delay and can realize more real time performance.

Further, since a plurality of video data are substantially the same scene, the server may manage and / or instruct the video data captured by each terminal to be mutually referred to. Alternatively, the server may receive the encoded data from each terminal and change the reference relationship among a plurality of data, or may correct or replace the picture itself and re-encode it. This makes it possible to generate streams with enhanced quality and efficiency of each piece of data.

Also, the server may deliver the video data after performing transcoding for changing the coding method of the video data. For example, the server may convert the encoding system of the MPEG system into the VP system, or the H.264 system. H.264. It may be converted to 265.

Thus, the encoding process can be performed by the terminal or one or more servers. Therefore, in the following, although the description such as "server" or "terminal" is used as the subject of processing, part or all of the processing performed by the server may be performed by the terminal, or the processing performed by the terminal Some or all may be performed on the server. In addition, with regard to these, the same applies to the decoding process.

[3D, multi-angle]
In recent years, it has been increasingly used to integrate and use different scenes captured by terminals such as a plurality of cameras ex113 and / or smartphone ex115 which are substantially synchronized with each other, or images or videos of the same scene captured from different angles. There is. The images captured by each terminal are integrated based on the relative positional relationship between the terminals acquired separately, or an area where the feature points included in the image coincide with each other.

The server not only encodes a two-dimensional moving image, but also automatically encodes a still image based on scene analysis of the moving image or at a time designated by the user and transmits it to the receiving terminal. It is also good. Furthermore, if the server can acquire relative positional relationship between the imaging terminals, the three-dimensional shape of the scene is not only determined based on the two-dimensional moving image but also the video of the same scene captured from different angles. Can be generated. Note that the server may separately encode three-dimensional data generated by a point cloud or the like, or an image to be transmitted to the receiving terminal based on a result of recognizing or tracking a person or an object using the three-dimensional data. Alternatively, it may be generated by selecting or reconfiguring from videos taken by a plurality of terminals.

In this way, the user can enjoy the scene by arbitrarily selecting each video corresponding to each photographing terminal, or from the three-dimensional data reconstructed using a plurality of images or videos, the video of the arbitrary viewpoint You can also enjoy the extracted content. Furthermore, the sound may be picked up from a plurality of different angles as well as the video, and the server may multiplex the sound from a specific angle or space with the video and transmit it according to the video.

Also, in recent years, content in which the real world and the virtual world are associated, such as Virtual Reality (VR) and Augmented Reality (AR), has also become widespread. In the case of VR images, the server may create viewpoint images for the right eye and for the left eye, respectively, and may perform coding to allow reference between each viewpoint video using Multi-View Coding (MVC) or the like. It may be encoded as another stream without reference. At the time of decoding of another stream, reproduction may be performed in synchronization with each other so that a virtual three-dimensional space is reproduced according to the viewpoint of the user.

In the case of an AR image, the server superimposes virtual object information in the virtual space on camera information in the real space based on the three-dimensional position or the movement of the user's viewpoint. The decoding apparatus may acquire or hold virtual object information and three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and create superimposed data by smoothly connecting. Alternatively, the decoding device transmits the motion of the user's viewpoint to the server in addition to the request for virtual object information, and the server creates superimposed data in accordance with the motion of the viewpoint received from the three-dimensional data held in the server. The superimposed data may be encoded and distributed to the decoding device. Note that the superimposed data has an α value indicating transparency as well as RGB, and the server sets the α value of a portion other than the object created from the three-dimensional data to 0 etc., and the portion is transparent , May be encoded. Alternatively, the server may set RGB values of predetermined values as a background, such as chroma key, and generate data in which the portion other than the object has a background color.

Similarly, the decryption processing of the distributed data may be performed by each terminal which is a client, may be performed by the server side, or may be performed sharing each other. As one example, one terminal may send a reception request to the server once, the content corresponding to the request may be received by another terminal and decoded, and the decoded signal may be transmitted to a device having a display. Data of high image quality can be reproduced by distributing processing and selecting appropriate content regardless of the performance of the communicable terminal itself. As another example, while receiving image data of a large size by a TV or the like, a viewer's personal terminal may decode and display a partial area such as a tile in which a picture is divided. Thereby, it is possible to confirm at hand the area in which the user is in charge or the area to be checked in more detail while sharing the whole image.

Also, from now on, for communication under connection using a delivery system standard such as MPEG-DASH under a situation where multiple short distance, middle distance or long distance wireless communication can be used regardless of indoor or outdoor. It is expected to receive content seamlessly while switching the appropriate data. As a result, the user can switch in real time while freely selecting not only his own terminal but also a decoding apparatus or display apparatus such as a display installed indoors and outdoors. In addition, decoding can be performed while switching between a terminal to be decoded and a terminal to be displayed, based on own position information and the like. This makes it possible to move while displaying map information on the wall surface or part of the ground of the next building in which the displayable device is embedded while moving to the destination. Also, access to encoded data over the network, such as encoded data being cached on a server that can be accessed in a short time from a receiving terminal, or copied to an edge server in a content delivery service, etc. It is also possible to switch the bit rate of the received data based on ease.

[Scalable coding]
Content switching will be described using a scalable stream compression-coded by applying the moving picture coding method shown in each of the above embodiments shown in FIG. The server may have a plurality of streams with the same content but different qualities as individual streams, but is temporally / spatial scalable which is realized by coding into layers as shown in the figure. The configuration may be such that the content is switched using the feature of the stream. That is, the decoding side determines low-resolution content and high-resolution content by determining which layer to decode depending on the internal factor of performance and external factors such as the state of the communication band. It can be switched freely and decoded. For example, when it is desired to view the continuation of the video being watched by the smartphone ex115 while moving on a device such as the Internet TV after returning home, the device only has to decode the same stream to different layers, so the burden on the server side Can be reduced.

Furthermore, as described above, the picture is encoded for each layer, and the enhancement layer includes meta information based on statistical information of the image, etc., in addition to the configuration for realizing the scalability in which the enhancement layer exists above the base layer. The decoding side may generate high-quality content by super-resolving a picture of the base layer based on the meta information. The super resolution may be either an improvement in the SN ratio at the same resolution or an expansion of the resolution. Meta information includes information for identifying linear or non-linear filter coefficients used for super-resolution processing, or information for identifying parameter values in filter processing used for super-resolution processing, machine learning or least squares operation, etc. .

Alternatively, the picture may be divided into tiles or the like according to the meaning of an object or the like in the image, and the decoding side may be configured to decode only a part of the area by selecting the tile to be decoded. Also, by storing the attribute of the object (person, car, ball, etc.) and the position in the image (coordinate position in the same image, etc.) as meta information, the decoding side can position the desired object based on the meta information And determine the tile that contains the object. For example, as shown in FIG. 119, meta information is stored using a data storage structure different from pixel data, such as an SEI message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.

Also, meta information may be stored in units of a plurality of pictures, such as streams, sequences, or random access units. As a result, the decoding side can acquire the time when a specific person appears in the video and the like, and can identify the picture in which the object exists and the position of the object in the picture by combining the information with the picture unit.

Web Page Optimization
FIG. 120 is a diagram showing an example of a display screen of a web page in the computer ex111 and the like. FIG. 121 is a diagram illustrating an example of a display screen of a web page in the smartphone ex115 or the like. As shown in FIGS. 120 and 121, the web page may include a plurality of link images which are links to image content, and the appearance differs depending on the browsing device. When multiple link images are visible on the screen, the display device until the user explicitly selects the link image, or until the link image approaches near the center of the screen or the entire link image falls within the screen The (decoding device) displays still images or I pictures of each content as link images, displays images such as gif animation with a plurality of still images or I pictures, etc., receives only the base layer Decode and display.

When the link image is selected by the user, the display device decodes the base layer with the highest priority. Note that the display device may decode up to the enhancement layer if there is information indicating that the content is scalable in the HTML configuring the web page. Also, in order to secure real-time capability, the display device decodes only forward referenced pictures (I picture, P picture, forward referenced only B picture) before the selection or when the communication band is very strict. And, by displaying, it is possible to reduce the delay between the decoding time of the leading picture and the display time (delay from the start of decoding of content to the start of display). In addition, the display device may roughly ignore the reference relationship of pictures and roughly decode all B pictures and P pictures with forward reference, and may perform normal decoding as time passes and the number of received pictures increases.

[Auto run]
In addition, when transmitting or receiving still image or video data such as two-dimensional or three-dimensional map information for automatic traveling or driving assistance of a car, the receiving terminal is added as image information belonging to one or more layers as meta information Information on weather or construction may also be received, and these may be correlated and decoded. The meta information may belong to the layer or may be simply multiplexed with the image data.

In this case, since a car including a receiving terminal, a drone or an airplane moves, the receiving terminal transmits the position information of the receiving terminal at the time of reception request to seamlessly receive and decode while switching the base stations ex106 to ex110. Can be realized. In addition, the receiving terminal can dynamically switch how much meta information is received or how much map information is updated according to the user's selection, the user's situation or the state of the communication band. become.

As described above, in the content providing system ex100, the client can receive, decode, and reproduce the encoded information transmitted by the user in real time.

[Distribution of personal content]
Further, in the content supply system ex100, not only high-quality and long-time content by a video distribution company but also unicast or multicast distribution of low-quality and short-time content by an individual is possible. In addition, such personal content is expected to increase in the future. In order to make the personal content more excellent, the server may perform the encoding process after performing the editing process. This can be realized, for example, with the following configuration.

At the time of shooting, the server performs recognition processing such as shooting error, scene search, meaning analysis, and object detection from the original image or encoded data after shooting in real time or by accumulation. Then, the server manually or automatically corrects out-of-focus or camera shake, etc. based on the recognition result, or a scene with low importance such as a scene whose brightness is low or out of focus compared with other pictures. Make edits such as deleting, emphasizing the edge of an object, or changing the color. The server encodes the edited data based on the edited result. It is also known that the audience rating drops when the shooting time is too long, and the server works not only with scenes with low importance as described above, but also moves as content becomes within a specific time range according to the shooting time. Scenes with a small amount of motion may be clipped automatically based on the image processing result. Alternatively, the server may generate and encode a digest based on the result of semantic analysis of the scene.

In some cases, there are cases where personal content may infringe copyright, author's personality right, portrait right, etc. as it is, and it is inconvenient for the individual, such as the range of sharing exceeds the intended range. There are also cases. Thus, for example, the server may change and encode the face of a person at the periphery of the screen, or the inside of a house, etc. into an image out of focus. In addition, the server recognizes whether or not the face of a person different from the person registered in advance appears in the image to be encoded, and if so, performs processing such as mosaicing the face portion. May be Alternatively, the user designates a person or background area desired to process an image from the viewpoint of copyright etc. as preprocessing or post-processing of encoding, and the server replaces the designated area with another video or blurs the focus. It is also possible to perform such processing. If it is a person, it is possible to replace the image of the face part while tracking the person in the moving image.

Also, since viewing of personal content with a small amount of data has a strong demand for real-time performance, the decoding apparatus first receives the base layer with the highest priority, and performs decoding and reproduction, although it depends on the bandwidth. The decoding device may receive the enhancement layer during this period, and may play back high-quality video including the enhancement layer if it is played back more than once, such as when playback is looped. In the case of a stream in which scalable coding is performed as described above, it is possible to provide an experience in which the stream gradually becomes smart and the image becomes better although it is a rough moving image when it is not selected or when it starts watching. Besides scalable coding, the same experience can be provided even if the coarse stream played back first and the second stream coded with reference to the first moving image are configured as one stream .

[Other use cases]
Also, these encoding or decoding processes are generally processed in an LSI ex 500 that each terminal has. The LSI ex 500 may be a single chip or a plurality of chips. Software for moving image encoding or decoding is incorporated in any recording medium (CD-ROM, flexible disk, hard disk, etc.) readable by computer ex111 or the like, and encoding or decoding is performed using the software. It is also good. Furthermore, when the smartphone ex115 is equipped with a camera, moving image data acquired by the camera may be transmitted. The moving image data at this time is data encoded by the LSI ex 500 included in the smartphone ex 115.

The LSI ex 500 may be configured to download and activate application software. In this case, the terminal first determines whether the terminal corresponds to the content coding scheme or has the ability to execute a specific service. If the terminal does not support the content encoding method or does not have the ability to execute a specific service, the terminal downloads the codec or application software, and then acquires and reproduces the content.

Further, the present invention is not limited to the content supply system ex100 via the Internet ex101, but also to a system for digital broadcasting at least a moving picture coding apparatus (image coding apparatus) or a moving picture decoding apparatus (image decoding apparatus) of the above embodiments. Can be incorporated. There is a difference in that it is multicast-oriented with respect to the configuration in which the content supply system ex100 can be easily unicasted, since multiplexed data in which video and sound are multiplexed is transmitted on broadcast radio waves using satellites etc. Similar applications are possible for the encoding process and the decoding process.

[Hardware configuration]
FIG. 122 is a diagram illustrating the smartphone ex115. Further, FIG. 123 is a diagram illustrating a configuration example of the smartphone ex115. The smartphone ex115 receives an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of taking video and still images, a video taken by the camera unit ex465, and the antenna ex450 And a display unit ex <b> 458 for displaying data obtained by decoding an image or the like. The smartphone ex115 further includes an operation unit ex466 that is a touch panel or the like, a voice output unit ex457 that is a speaker or the like for outputting voice or sound, a voice input unit ex456 that is a microphone or the like for inputting voice, Identify the user, the memory unit ex 467 capable of storing encoded video or still image, recorded voice, received video or still image, encoded data such as mail, or decoded data, and specify a network, etc. And a slot unit ex464 that is an interface unit with the SIM ex 468 for authenticating access to various data. Note that an external memory may be used instead of the memory unit ex467.

Further, a main control unit ex460 that integrally controls the display unit ex458 and the operation unit ex466, a power supply circuit unit ex461, an operation input control unit ex462, a video signal processing unit ex455, a camera interface unit ex463, a display control unit ex459, / Demodulation unit ex452, multiplexing / demultiplexing unit ex453, audio signal processing unit ex454, slot unit ex464, and memory unit ex467 are connected via a bus ex470.

When the power supply key is turned on by the user's operation, the power supply circuit unit ex461 activates the smartphone ex115 to an operable state by supplying power from the battery pack to each unit.

The smartphone ex115 performs processing such as call and data communication based on control of the main control unit ex460 having a CPU, a ROM, a RAM, and the like. At the time of a call, the audio signal collected by the audio input unit ex456 is converted to a digital audio signal by the audio signal processing unit ex454, spread spectrum processing is performed by the modulation / demodulation unit ex452, and digital analog conversion is performed by the transmission / reception unit ex451. After processing and frequency conversion processing, transmission is performed via the antenna ex450. Further, the received data is amplified and subjected to frequency conversion processing and analog-to-digital conversion processing, subjected to spectrum despreading processing by modulation / demodulation unit ex452, and converted to an analog sound signal by sound signal processing unit ex454. Output from In the data communication mode, text, still images, or video data are sent to the main control unit ex460 via the operation input control unit ex462 by the operation of the operation unit ex466 or the like of the main unit, and transmission and reception processing is similarly performed. In the case of transmitting video, still images, or video and audio in the data communication mode, the video signal processing unit ex 455 executes the video signal stored in the memory unit ex 467 or the video signal input from the camera unit ex 465 as described above. The video data is compressed and encoded by the moving picture encoding method shown in the form, and the encoded video data is sent to the multiplexing / demultiplexing unit ex453. Further, the audio signal processing unit ex454 encodes an audio signal collected by the audio input unit ex456 while capturing a video or a still image with the camera unit ex465, and sends the encoded audio data to the multiplexing / demultiplexing unit ex453. Do. The multiplexing / demultiplexing unit ex453 multiplexes the encoded video data and the encoded audio data according to a predetermined method, and performs modulation processing and conversion by the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the transmission / reception unit ex451. It processes and transmits via antenna ex450.

When a video attached to an e-mail or a chat or a video linked to a web page or the like is received, the multiplexing / demultiplexing unit ex453 multiplexes in order to decode multiplexed data received via the antenna ex450. By separating the data, the multiplexed data is divided into a bit stream of video data and a bit stream of audio data, and the encoded video data is supplied to the video signal processing unit ex455 via the synchronization bus ex470, and The converted audio data is supplied to the audio signal processing unit ex 454. The video signal processing unit ex 455 decodes the video signal by the moving picture decoding method corresponding to the moving picture coding method described in each of the above embodiments, and is linked from the display unit ex 458 via the display control unit ex 459. An image or a still image included in the moving image file is displayed. The audio signal processing unit ex 454 decodes the audio signal, and the audio output unit ex 457 outputs the audio. Furthermore, since real-time streaming is widespread, depending on the user's situation, it may happen that sound reproduction is not socially appropriate. Therefore, as an initial value, it is preferable to be configured to reproduce only the video data without reproducing the audio signal. Audio may be synchronized and played back only when the user performs an operation such as clicking on video data.

Also, although the smartphone ex115 has been described as an example, in addition to a transceiving terminal having both an encoder and a decoder as a terminal, a transmitting terminal having only the encoder and a receiver having only the decoder There are three possible implementation forms: terminals. Furthermore, in the digital broadcasting system, it has been described that multiplexed data in which audio data is multiplexed with video data is received or transmitted, but in multiplexed data, character data related to video other than audio data is also described. It may be multiplexed, or video data itself may be received or transmitted, not multiplexed data.

Although the main control unit ex 460 including the CPU is described as controlling the encoding or decoding process, the terminal often includes a GPU. Therefore, a configuration in which a large area is collectively processed using the performance of the GPU may be performed using a memory shared by the CPU and the GPU, or a memory whose address is managed so as to be commonly used. As a result, coding time can be shortened, real time property can be secured, and low delay can be realized. In particular, it is efficient to perform processing of motion search, deblock filter, sample adaptive offset (SAO), and transform / quantization collectively in units of pictures or the like on the GPU instead of the CPU.

The present disclosure is applicable to, for example, television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, and the like.

Reference Signs List 100 encoder 102 division unit 104 subtraction unit 106 transformation unit 108 quantization unit 110 entropy encoding unit 112, 204 inverse quantization unit 114, 206 inverse transformation unit 116, 208 addition unit 118, 210 block memory 120, 212 loop filter Unit 122, 214 Frame memory 124, 216 Intra prediction unit 126, 218 Inter prediction unit 128, 220 Prediction control unit 200 Decoding device 202 Entropy decoding unit

Claims (36)

An encoding apparatus for encoding an image encoding target block, the encoding apparatus comprising:
Circuit,
With memory,
The circuit uses the memory to
Performing a linear transformation from the residual of the block to be encoded to the primary coefficient;
It is determined whether to apply a quadratic transform to the encoding target block,
(I) When the second transformation is not applied, the quantization first order coefficient is calculated by performing first quantization on the first order coefficient, and (ii) the first order coefficient is applied when the second transformation is applied Calculating a quantized secondary coefficient by performing a secondary conversion from the coefficient to a secondary coefficient, and performing a second quantization different from the first quantization on the secondary coefficient;
Generating a coded bit stream by coding the quantized primary coefficient or the quantized secondary coefficient;
Encoding device. The first quantization is weighted quantization using a first quantization matrix,
The second quantization is a weighted quantization using a second quantization matrix different from the first quantization matrix.
The encoding device according to claim 1. The circuit further comprises
Writing the first quantization matrix and the second quantization matrix to the coded bit stream;
The encoding device according to claim 2. The primary coefficients include one or more first primary coefficients and one or more second primary coefficients.
The quadratic transform is applied to the one or more first linear coefficients, and not to the one or more second linear coefficients.
The second quantization matrix includes one or more first component values corresponding to the one or more first primary coefficients, and one or more second component values corresponding to the one or more second primary coefficients. Including
Each of the one or more second component values of the second quantization matrix corresponds to a corresponding component value of the first quantization matrix,
In the writing of the second quantization matrix, of the one or more first component values and the one or more second component values, only the one or more first component values are written to the encoded bit stream.
The encoding device according to claim 3. In the quadratic transformation, a plurality of predetermined bases are selectively used,
The coded bit stream includes a plurality of second quantization matrices corresponding to the plurality of bases,
In the second quantization, a second quantization matrix corresponding to the basis used for the second transformation is selected from the plurality of second quantization matrices.
The encoding device according to claim 3. The first quantization matrix and the second quantization matrix are predefined in a standardization standard,
The encoding device according to claim 2. The circuit further comprises
Deriving the second quantization matrix from the first quantization matrix,
The encoding device according to claim 2. The primary coefficients include one or more first primary coefficients and one or more second primary coefficients.
The quadratic transform is applied to the one or more first linear coefficients, and not to the one or more second linear coefficients.
The second quantization matrix includes one or more first component values corresponding to the one or more first primary coefficients, and one or more second component values corresponding to the one or more second primary coefficients. Including
Each of the one or more second component values of the second quantization matrix corresponds to a corresponding component value of the first quantization matrix,
Derivation of the second quantization matrix derives the one or more first component values of the second quantization matrix from the first quantization matrix.
The encoding device according to claim 7. The second quantization matrix is derived by applying the second transformation to the first quantization matrix
The encoding device according to claim 7. The circuit further comprises
A third quantization matrix is derived from the first quantization matrix, and each component value of the third quantization matrix is larger as a corresponding component value of the first quantization matrix is smaller,
Deriving a fourth quantization matrix by applying the second transformation to the third quantization matrix;
A fifth quantization matrix is derived from the fourth quantization matrix as the second quantization matrix, and each component value of the fifth quantization matrix is larger as a corresponding component value of the fourth quantization matrix is smaller. ,
The encoding device according to claim 7. Each component value of the third quantization matrix is a reciprocal of a corresponding component value of the first quantization matrix,
Each component value of the fifth quantization matrix is a reciprocal of a corresponding component value of the fourth quantization matrix.
An encoding device according to claim 10. The first quantization is weighted quantization using a quantization matrix,
The second quantization is unweighted quantization that does not use a quantization matrix.
The encoding device according to claim 1. The first quantization is weighted quantization using a first quantization matrix,
In the secondary conversion, (i) weighted primary coefficients are calculated by multiplying each of the primary coefficients by the corresponding component value of the weight matrix, and (ii) the weighted primary coefficients are converted to secondary coefficients. And
The second quantization divides each of the secondary coefficients by a common quantization step to the secondary coefficients.
The encoding device according to claim 1. The circuit further comprises
Deriving the weight matrix from the first quantization matrix,
An encoding apparatus according to claim 13. The circuit further comprises
Deriving the common quantization step from quantization parameters for the block to be coded,
An encoding apparatus according to claim 13 or 14. A coding method for coding a coding target block of an image, comprising:
Performing a linear transformation from the residual of the block to be encoded to the primary coefficient;
It is determined whether to apply a quadratic transform to the encoding target block,
(I) When the second transformation is not applied, the quantization first order coefficient is calculated by performing first quantization on the first order coefficient, and (ii) the first order coefficient is applied when the second transformation is applied Calculating a quantized secondary coefficient by performing a secondary conversion from the coefficient to a secondary coefficient, and performing a second quantization different from the first quantization on the secondary coefficient;
Generating a coded bit stream by coding the quantized primary coefficient or the quantized secondary coefficient;
Encoding method. An encoding apparatus for encoding an image encoding target block, the encoding apparatus comprising:
Circuit,
With memory,
The circuit uses the memory to
Linearly transform the residual of the block to be encoded into primary coefficients;
It is determined whether to apply a quadratic transform to the encoding target block,
(I) When the second transformation is not applied, a first quantization first order coefficient is calculated by performing first quantization on the first order coefficient, and (ii) when the second transformation is applied: Second quantization is performed on the first-order coefficient to calculate a second quantization first-order coefficient, and second-order conversion from the second quantization first-order coefficient to a quantization second-order coefficient is performed,
Generating a coded bit stream by coding the first quantized primary coefficient or the quantized secondary coefficient;
Encoding device. A coding method for coding a coding target block of an image, comprising:
Linearly transform the residual of the block to be encoded into primary coefficients;
It is determined whether to apply a quadratic transform to the encoding target block,
(I) When the second transformation is not applied, a first quantization first order coefficient is calculated by performing first quantization on the first order coefficient, and (ii) when the second transformation is applied: Second quantization is performed on the first-order coefficient to calculate a second quantization first-order coefficient, and second-order conversion from the second quantization first-order coefficient to a quantization second-order coefficient is performed,
Generating a coded bit stream by coding the first quantized primary coefficient or the quantized secondary coefficient;
Encoding method. A decoding apparatus for decoding a decoding target block of an image, the decoding apparatus comprising:
Circuit,
With memory,
The circuit uses the memory to
Decoding the quantization coefficient of the block to be decoded from a coded bit stream;
Determining whether to apply an inverse quadratic transform to the block to be decoded;
When the inverse quadratic transform is not applied, primary coefficients are calculated by performing first inverse quantization on the quantized coefficients, and the inverse linear transform from the primary coefficients to the residual of the block to be decoded is calculated. Do,
When the inverse quadratic transform is applied, a second-order coefficient is calculated by performing second inverse quantization different from the first inverse quantization on the quantization coefficient, and a first-order coefficient is calculated from the second-order coefficient Perform an inverse quadratic transformation of the primary coefficient to a residual of the block to be decoded.
Decoding device. The first inverse quantization is a weighted inverse quantization using a first quantization matrix,
The second inverse quantization is a weighted inverse quantization using a second quantization matrix different from the first quantization matrix.
The decoding device according to claim 19. The circuit further comprises
Decipher the first quantization matrix and the second quantization matrix from the coded bit stream,
A decoding device according to claim 20. The second order coefficient includes one or more first second order coefficients and one or more second second order coefficients,
The inverse quadratic transform is applied to the one or more first quadratic coefficients and is not applied to the one or more second quadratic coefficients.
The second quantization matrix includes one or more first component values corresponding to the one or more first secondary coefficients, and one or more second component values corresponding to the one or more second secondary coefficients. And, and
Each of the one or more second component values of the second quantization matrix corresponds to a corresponding component value of the first quantization matrix,
In the interpretation of the second quantization matrix, only the one or more first component positions among the one or more first component values and the one or more second component values are interpreted from the encoded bit stream.
The decoding device according to claim 21. In the inverse quadratic transformation, a plurality of predetermined bases are selectively used,
The coded bit stream includes a plurality of second quantization matrices corresponding to the plurality of bases,
In the second inverse quantization, a second quantization matrix corresponding to the basis used for the inverse quadratic transformation is selected from the plurality of second quantization matrices.
The decoding device according to claim 21. The first quantization matrix and the second quantization matrix are predefined in a standardization standard,
A decoding device according to claim 20. The circuit further comprises
Deriving the second quantization matrix from the first quantization matrix,
A decoding device according to claim 20. The second order coefficient includes one or more first second order coefficients and one or more second second order coefficients,
The inverse quadratic transform is applied to the one or more first quadratic coefficients and is not applied to the one or more second quadratic coefficients.
The second quantization matrix includes one or more first component values corresponding to the one or more first secondary coefficients, and one or more second component values corresponding to the one or more second secondary coefficients. And, and
Each of the one or more second component values of the second quantization matrix corresponds to a corresponding component value of the first quantization matrix,
In the derivation of the second quantization matrix, the one or more first component positions are derived from the first quantization matrix,
The decoding device according to claim 25. The second quantization matrix is derived by applying a quadratic transform to the first quantization matrix
The decoding device according to claim 25. The circuit further comprises
A third quantization matrix is derived from the first quantization matrix, and each component value of the third quantization matrix is larger as a corresponding component value of the first quantization matrix is smaller,
Deriving a fourth quantization matrix by applying a quadratic transform to the third quantization matrix;
A fifth quantization matrix is derived from the fourth quantization matrix as the second quantization matrix, and each component value of the fifth quantization matrix is larger as a corresponding component value of the fourth quantization matrix is smaller. ,
The decoding device according to claim 25. Each component value of the third quantization matrix is a reciprocal of a corresponding component value of the first quantization matrix,
Each component value of the fifth quantization matrix is a reciprocal of a corresponding component value of the fourth quantization matrix.
The decoding device according to claim 28. The first inverse quantization is weighted inverse quantization using a quantization matrix,
The second dequantization is unweighted dequantization without a quantization matrix,
The decoding device according to claim 19. The first inverse quantization is a weighted inverse quantization using a first quantization matrix,
In the second inverse quantization, the secondary coefficient is calculated by multiplying each of the quantization coefficients by a common quantization step for the quantization coefficients;
In said inverse quadratic transformation, said primary coefficients are (i) inverse transformed to weighted primary coefficients and (ii) each of said weighted primary coefficients is divided by the corresponding component value of the weighting matrix. Calculate
The decoding device according to claim 19. The circuit further comprises
Deriving the weight matrix from the first quantization matrix,
The decoding device according to claim 31. The circuit further comprises
Deriving the common quantization step from quantization parameters for the block to be decoded,
33. The decoding device according to claim 31 or 32. A decoding method for decoding a decoding target block of an image, comprising:
Decoding the quantization coefficient of the block to be decoded from a coded bit stream;
Determining whether to apply an inverse quadratic transform to the block to be decoded;
When the inverse quadratic transform is not applied, primary coefficients are calculated by performing first inverse quantization on the quantized coefficients, and the inverse linear transform from the primary coefficients to the residual of the block to be decoded is calculated. Do,
When the inverse quadratic transform is applied, a second-order coefficient is calculated by performing second inverse quantization different from the first inverse quantization on the quantization coefficient, and a first-order coefficient is calculated from the second-order coefficient Perform an inverse quadratic transformation of the primary coefficient to a residual of the block to be decoded.
Decryption method. A decoding apparatus for decoding a decoding target block of an image, the decoding apparatus comprising:
Circuit,
With memory,
The circuit uses the memory to
Decoding the quantization coefficient of the block to be decoded from a coded bit stream;
Determining whether to apply an inverse quadratic transform to the block to be decoded;
When the inverse quadratic transform is not applied, primary coefficients are calculated by performing first inverse quantization on the quantized coefficients, and the inverse linear transform from the primary coefficients to the residual of the block to be decoded is calculated. Do,
When the inverse quadratic transform is applied, an inverse quadratic transform is performed on the quantized coefficient to a quantized primary coefficient, and a second inverse quantization is performed on the quantized primary coefficient to calculate a primary coefficient. Performing an inverse linear transformation from the primary coefficient to the residual of the block to be decoded,
Decoding device. A decoding method for decoding a decoding target block of an image, comprising:
Decoding the quantization coefficient of the block to be decoded from a coded bit stream;
Determining whether to apply an inverse quadratic transform to the block to be decoded;
When the inverse quadratic transform is not applied, primary coefficients are calculated by performing first inverse quantization on the quantized coefficients, and the inverse linear transform from the primary coefficients to the residual of the block to be decoded is calculated. Do,
When the inverse quadratic transform is applied, an inverse quadratic transform is performed on the quantized coefficient to a quantized primary coefficient, and a second inverse quantization is performed on the quantized primary coefficient to calculate a primary coefficient. Performing an inverse linear transformation from the primary coefficient to the residual of the block to be decoded,
Decryption method.

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